Apparatus and method for sending and receiving broadcast signals

ABSTRACT

Disclosed herein is a broadcast signal transmitter. The broadcast signal transmitter according to an embodiment of the present invention includes an input formatting module configured to perform baseband formatting and to output at least one Physical Layer Pipe (PLP) data, a BICM module configured to perform error-correction processing on the PLP data, a framing and interleaving module configured to interleave the PLP data and to generate a signal frame, and a waveform generation module configured to insert a preamble into the signal frame and to generate a broadcast signal by OFDM-modulate the signal frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Provisional Application No.62/197,542 filed on 27 Jul. 2015 in U.S. Provisional Application No.62/199,844 filed on 31 Jul. 2015 in U.S. Provisional Application No.62/201,531 filed on 5 Aug. 2015 in US and Provisional Application No.62/198,117 filed on 28 Jul. 2015 in US, the entire contents of which ishereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an apparatus for transmitting broadcastsignals, an apparatus for receiving broadcast signals and methods fortransmitting and receiving broadcast signals.

Discussion of the Related Art

As analog broadcast signal transmission comes to an end, varioustechnologies for transmitting/receiving digital broadcast signals arebeing developed. A digital broadcast signal may include a larger amountof video/audio data than an analog broadcast signal and further includevarious types of additional data in addition to the video/audio data.

That is, a digital broadcast system can provide HD (high definition)images, multi-channel audio and various additional services. However,data transmission efficiency for transmission of large amounts of data,robustness of transmission/reception networks and network flexibility inconsideration of mobile reception equipment need to be improved fordigital broadcast.

SUMMARY OF THE INVENTION

A broadcast signal transmitter for processing a broadcast signalincluding signaling information according to an embodiment of thepresent invention includes an input formatting module configured toinput process input data and to output at least one Physical Layer Pipe(PLP) data, a Bit Interleaved and Coded Modulation (BICM) moduleconfigured to perform error correction processing on the PLP data, aframing module configured to generate a signal frame including the PLPdata, the signal frame including a preamble and at least one subframe, apilot insertion module configured to insert pilots into the signalframe, and an Inverse Fast Fourier Transform (IFFT) module configured toOFDM-modulate the signal frame. The subframe includes data symbols andat least one Subframe Boundary Symbol (SBS), and the SBS includes datacarriers and subframe boundary pilots.

In the broadcast signal transmitter according to an embodiment of thepresent invention, the data symbols of the subframe may includeScattered Pilots (SPs), amplitude of the SPs may be determined based onan SP boosting parameter indicating a power boosting level of the SPs,and amplitude of the subframe boundary pilots may be determined based onthe SP boosting parameter.

In the broadcast signal transmitter according to an embodiment of thepresent invention, the subframe boundary pilots may be placed based on apilot separation in the frequency direction of an SP pattern for thesubframe, and the data carriers of the SBS may include the specificnumber of active data carriers and the specific number of null carriers.

In the broadcast signal transmitter according to an embodiment of thepresent invention, the number of active data carriers may be determinedbased on the SP boosting parameter.

In the broadcast signal transmitter according to an embodiment of thepresent invention, the number of null carriers may be determined basedon the amplitude of the SPs.

In the broadcast signal transmitter according to an embodiment of thepresent invention, the number of null carriers may be obtained bysubtracting the number of active data carriers from the number of datacarriers.

In the broadcast signal transmitter according to an embodiment of thepresent invention, the active data carriers may be placed at the centerof the data carriers, and half of the null cells may be placed at theeach band edges of the data carriers.

Furthermore, a method of transmitting a broadcast signal according to anembodiment of the present invention includes receiving and processinginput data and to output at least one Physical Layer Pipe (PLP) data,performing error correction processing on the PLP data, generating asignal frame including the PLP data, the signal frame including apreamble and at least one subframe, inserting pilots into the signalframe, and OFDM-modulating the signal frame. The subframe includes datasymbols and at least one Subframe Boundary Symbol (SBS), and the SBSincludes data carriers and subframe boundary pilots.

The present invention can process data according to servicecharacteristics to control QoS (Quality of Services) for each service orservice component, thereby providing various broadcast services.

The present invention can achieve transmission flexibility bytransmitting various broadcast services through the same RF signalbandwidth.

The present invention can improve data transmission efficiency andincrease robustness of transmission/reception of broadcast signals usinga MIMO system.

According to the present invention, it is possible to provide broadcastsignal transmission and reception methods and apparatus capable ofreceiving digital broadcast signals without error even with mobilereception equipment or in an indoor environment.

Further aspects and effects of the present invention will be describedmore detail with embodiments in belows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

FIG. 2 illustrates an input formatting block according to one embodimentof the present invention.

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention.

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention.

FIG. 5 illustrates a BICM block according to an embodiment of thepresent invention.

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention.

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention.

FIG. 8 illustrates an OFDM generation block according to an embodimentof the present invention.

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

FIG. 10 illustrates a frame structure according to an embodiment of thepresent invention.

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention.

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention.

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention.

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention.

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention.

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention.

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention.

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention.

FIG. 19 illustrates FIC mapping according to an embodiment of thepresent invention.

FIG. 20 illustrates a type of DP according to an embodiment of thepresent invention.

FIG. 21 illustrates DP mapping according to an embodiment of the presentinvention.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention.

FIG. 23 illustrates a bit interleaving according to an embodiment of thepresent invention.

FIG. 24 illustrates a cell-word demultiplexing according to anembodiment of the present invention.

FIG. 25 illustrates a time interleaving according to an embodiment ofthe present invention.

FIG. 26 illustrates a basic operation of a twisted row-column blockinterleaver according to an exemplary embodiment of the presentinvention.

FIG. 27 illustrates an operation of a twisted row-column blockinterleaver according to another exemplary embodiment of the presentinvention.

FIG. 28 illustrates a diagonal reading pattern of the twisted row-columnblock interleaver according to the exemplary embodiment of the presentinvention.

FIG. 29 illustrates XFECBLOCK interleaved from each interleaving arrayaccording to an exemplary embodiment of the present invention.

FIG. 30 shows the configuration of a broadcast signal transmitteraccording to another embodiment of the present invention.

FIG. 31 shows the structure of a signal frame according to an embodimentof the present invention.

FIG. 32 shows the structure of a signal frame according to an embodimentof the present invention.

FIG. 33 shows the pilot structure of a signal frame according to anembodiment of the present invention.

FIGS. 34 and 35 show SP boosting information according to an embodimentof the present invention.

FIGS. 36 and 37 show preamble pilot boosting information according to anembodiment of the present invention.

FIG. 38 shows the SP power boosting levels of a frame boundary symbol.

FIG. 39 shows the Number of Active carriers (NoA) for a normal datasymbol according to an embodiment of the present invention.

FIG. 40 shows the number of pilots of an SBS “N_SP,SBS” according to anembodiment of the present invention.

FIG. 41 shows the number of data carriers of an SBS according to anembodiment of the present invention.

FIG. 42 shows the number of CPs per symbol according to an embodiment ofthe present invention.

FIGS. 43 to 47 show the number of active data carriers of an SBS“NoA_SBS” depending on an NoC reduction coefficient “C_red_coeff”according to an embodiment of the present invention.

FIG. 48 shows a method of calculating the number of null carriers andpower normalization according to the method according to an embodimentof the present invention.

FIG. 49 shows a method of mapping the null carriers of an SBS accordingto an embodiment of the present invention.

FIG. 50 shows a method of mapping the null carriers of an SBS accordingto another embodiment of the present invention.

FIG. 51 shows a method of mapping the null carriers of an SBS accordingto another embodiment of the present invention.

FIG. 52 shows a method of mapping the null carriers of an SBS accordingto another embodiment of the present invention.

FIG. 53 shows a method of mapping null carriers according to anotherembodiment of the present invention.

FIG. 54 shows a method of transmitting a broadcast signal according toan embodiment of the present invention.

FIG. 55 shows the synchronization and demodulation module of thebroadcast signal receiver according to an embodiment of the presentinvention.

FIG. 56 shows a method of receiving a broadcast signal according to anembodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The detailed description, which will be given below withreference to the accompanying drawings, is intended to explain exemplaryembodiments of the present invention, rather than to show the onlyembodiments that can be implemented according to the present invention.The following detailed description includes specific details in order toprovide a thorough understanding of the present invention. However, itwill be apparent to those skilled in the art that the present inventionmay be practiced without such specific details.

Although most terms used in the present invention have been selectedfrom general ones widely used in the art, some terms have beenarbitrarily selected by the applicant and their meanings are explainedin detail in the following description as needed. Thus, the presentinvention should be understood based upon the intended meanings of theterms rather than their simple names or meanings. Also, the term blockand module are used similarly to indicate logical/functional unit ofparticular signal/data processing.

The present invention provides apparatuses and methods for transmittingand receiving broadcast signals for future broadcast services. Futurebroadcast services according to an embodiment of the present inventioninclude a terrestrial broadcast service, a mobile broadcast service, aUHDTV service, etc. The present invention may process broadcast signalsfor the future broadcast services through non-MIMO (Multiple InputMultiple Output) or MIMO according to one embodiment. A non-MIMO schemeaccording to an embodiment of the present invention may include a MISO(Multiple Input Single Output) scheme, a SISO (Single Input SingleOutput) scheme, etc.

While MISO or MIMO uses two antennas in the following for convenience ofdescription, the present invention is applicable to systems using two ormore antennas.

The present invention may defines three physical layer (PL)profiles—base, handheld and advanced profiles—each optimized to minimizereceiver complexity while attaining the performance required for aparticular use case. The physical layer (PHY) profiles are subsets ofall configurations that a corresponding receiver should implement.

The three PHY profiles share most of the functional blocks but differslightly in specific blocks and/or parameters. Additional PHY profilescan be defined in the future. For the system evolution, future profilescan also be multiplexed with the existing profiles in a single RFchannel through a future extension frame (FEF). The details of each PHYprofile are described below.

1. Base Profile

The base profile represents a main use case for fixed receiving devicesthat are usually connected to a roof-top antenna. The base profile alsoincludes portable devices that could be transported to a place butbelong to a relatively stationary reception category. Use of the baseprofile could be extended to handheld devices or even vehicular by someimproved implementations, but those use cases are not expected for thebase profile receiver operation.

Target SNR range of reception is from approximately 10 to 20 dB, whichincludes the 15 dB SNR reception capability of the existing broadcastsystem (e.g. ATSC A/53). The receiver complexity and power consumptionis not as critical as in the battery-operated handheld devices, whichwill use the handheld profile. Key system parameters for the baseprofile are listed in below table 1.

TABLE 1 LDPC codeword length 16K, 64K bits Constellation size 4~10 bpcu(bits per channel use) Time de-interleaving memory size ≦2¹⁹ data cellsPilot patterns Pilot pattern for fixed reception FFT size 16K, 32Kpoints

2. Handheld Profile

The handheld profile is designed for use in handheld and vehiculardevices that operate with battery power. The devices can be moving withpedestrian or vehicle speed. The power consumption as well as thereceiver complexity is very important for the implementation of thedevices of the handheld profile. The target SNR range of the handheldprofile is approximately 0 to 10 dB, but can be configured to reachbelow 0 dB when intended for deeper indoor reception.

In addition to low SNR capability, resilience to the Doppler Effectcaused by receiver mobility is the most important performance attributeof the handheld profile. Key system parameters for the handheld profileare listed in the below table 2.

TABLE 2 LDPC codeword length 16K bits Constellation size 2~8 bpcu Timede-interleaving memory size ≦2¹⁸ data cells Pilot patterns Pilotpatterns for mobile and indoor reception FFT size 8K, 16K points

3. Advanced Profile

The advanced profile provides highest channel capacity at the cost ofmore implementation complexity. This profile requires using MIMOtransmission and reception, and UHDTV service is a target use case forwhich this profile is specifically designed. The increased capacity canalso be used to allow an increased number of services in a givenbandwidth, e.g., multiple SDTV or HDTV services.

The target SNR range of the advanced profile is approximately 20 to 30dB. MIMO transmission may initially use existing elliptically-polarizedtransmission equipment, with extension to full-power cross-polarizedtransmission in the future. Key system parameters for the advancedprofile are listed in below table 3.

TABLE 3 LDPC codeword length 16K, 64K bits Constellation size 8~12 bpcuTime de-interleaving memory size ≦2¹⁹ data cells Pilot patterns Pilotpattern for fixed reception FFT size 16K, 32K points

In this case, the base profile can be used as a profile for both theterrestrial broadcast service and the mobile broadcast service. That is,the base profile can be used to define a concept of a profile whichincludes the mobile profile. Also, the advanced profile can be dividedadvanced profile for a base profile with MIMO and advanced profile for ahandheld profile with MIMO. Moreover, the three profiles can be changedaccording to intention of the designer.

The following terms and definitions may apply to the present invention.The following terms and definitions can be changed according to design.

auxiliary stream: sequence of cells carrying data of as yet undefinedmodulation and coding, which may be used for future extensions or asrequired by broadcasters or network operators

base data pipe: data pipe that carries service signaling data

baseband frame (or BBFRAME): set of Kbch bits which form the input toone FEC encoding process (BCH and LDPC encoding)

cell: modulation value that is carried by one carrier of the OFDMtransmission

coded block: LDPC-encoded block of PLS1 data or one of the LDPC-encodedblocks of PLS2 data

data pipe: logical channel in the physical layer that carries servicedata or related metadata, which may carry one or multiple service(s) orservice component(s).

data pipe unit: a basic unit for allocating data cells to a DP in aframe.

data symbol: OFDM symbol in a frame which is not a preamble symbol (theframe signaling symbol and frame edge symbol is included in the datasymbol)

DP_ID: this 8-bit field identifies uniquely a DP within the systemidentified by the SYSTEM_ID

dummy cell: cell carrying a pseudo-random value used to fill theremaining capacity not used for PLS signaling, DPs or auxiliary streams

emergency alert channel: part of a frame that carries EAS informationdata

frame: physical layer time slot that starts with a preamble and endswith a frame edge symbol

frame repetition unit: a set of frames belonging to same or differentphysical layer profile including a FEF, which is repeated eight times ina super-frame

fast information channel: a logical channel in a frame that carries themapping information between a service and the corresponding base DP

FECBLOCK: set of LDPC-encoded bits of a DP data

FFT size: nominal FFT size used for a particular mode, equal to theactive symbol period Ts expressed in cycles of the elementary period T

frame signaling symbol: OFDM symbol with higher pilot density used atthe start of a frame in certain combinations of FFT size, guard intervaland scattered pilot(sp) pattern, which carries a part of the PLS data

frame edge symbol: OFDM symbol with higher pilot density used at the endof a frame in certain combinations of FFT size, guard interval andscattered pilot pattern

frame-group: the set of all the frames having the same PHY profile typein a super-frame.

future extension frame: physical layer time slot within the super-framethat could be used for future extension, which starts with a preamble

Futurecast UTB system: proposed physical layer broadcasting system, ofwhich the input is one or more MPEG2-TS or IP or general stream(s) andof which the output is an RF signal

input stream: A stream of data for an ensemble of services delivered tothe end users by the system.

normal data symbol: data symbol excluding the frame signaling symbol andthe frame edge symbol

PHY profile: subset of all configurations that a corresponding receivershould implement

PLS: physical layer signaling data consisting of PLS1 and PLS2

PLS1: a first set of PLS data carried in the FSS symbols having a fixedsize, coding and modulation, which carries basic information about thesystem as well as the parameters needed to decode the PLS2

NOTE: PLS1 data remains constant for the duration of a frame-group.

PLS2: a second set of PLS data transmitted in the FSS symbol, whichcarries more detailed PLS data about the system and the DPs

PLS2 dynamic data: PLS2 data that may dynamically change frame-by-frame

PLS2 static data: PLS2 data that remains static for the duration of aframe-group

preamble signaling data: signaling data carried by the preamble symboland used to identify the basic mode of the system

preamble symbol: fixed-length pilot symbol that carries basic PLS dataand is located in the beginning of a frame

NOTE: The preamble symbol is mainly used for fast initial band scan todetect the system signal, its timing, frequency offset, and FFT-size.

reserved for future use: not defined by the present document but may bedefined in future

super-frame: set of eight frame repetition units

time interleaving block (TI block): set of cells within which timeinterleaving is carried out, corresponding to one use of the timeinterleaver memory

TI group: unit over which dynamic capacity allocation for a particularDP is carried out, made up of an integer, dynamically varying number ofXFECBLOCKs

NOTE: The TI group may be mapped directly to one frame or may be mappedto multiple frames. It may contain one or more TI blocks.

Type 1 DP: DP of a frame where all DPs are mapped into the frame in TDMfashion

Type 2 DP: DP of a frame where all DPs are mapped into the frame in FDMfashion

XFECBLOCK: set of Ncells cells carrying all the bits of one LDPCFECBLOCK

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

The apparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can includean input formatting block 1000, a BICM (Bit interleaved coding &modulation) block 1010, a frame structure block 1020, an OFDM(Orthogonal Frequency Division Multiplexing) generation block 1030 and asignaling generation block 1040. A description will be given of theoperation of each module of the apparatus for transmitting broadcastsignals.

IP stream/packets and MPEG2-TS are the main input formats, other streamtypes are handled as General Streams. In addition to these data inputs,Management Information is input to control the scheduling and allocationof the corresponding bandwidth for each input stream. One or multiple TSstream(s), IP stream(s) and/or General Stream(s) inputs aresimultaneously allowed.

The input formatting block 1000 can demultiplex each input stream intoone or multiple data pipe(s), to each of which an independent coding andmodulation is applied. The data pipe (DP) is the basic unit forrobustness control, thereby affecting quality-of-service (QoS). One ormultiple service(s) or service component(s) can be carried by a singleDP. Details of operations of the input formatting block 1000 will bedescribed later.

The data pipe is a logical channel in the physical layer that carriesservice data or related metadata, which may carry one or multipleservice(s) or service component (s).

Also, the data pipe unit: a basic unit for allocating data cells to a DPin a frame.

In the BICM block 1010, parity data is added for error correction andthe encoded bit streams are mapped to complex-value constellationsymbols. The symbols are interleaved across a specific interleavingdepth that is used for the corresponding DP. For the advanced profile,MIMO encoding is performed in the BICM block 1010 and the additionaldata path is added at the output for MIMO transmission. Details ofoperations of the BICM block 1010 will be described later.

The Frame Building block 1020 can map the data cells of the input DPsinto the OFDM symbols within a frame. After mapping, the frequencyinterleaving is used for frequency-domain diversity, especially tocombat frequency-selective fading channels. Details of operations of theFrame Building block 1020 will be described later.

After inserting a preamble at the beginning of each frame, the OFDMGeneration block 1030 can apply conventional OFDM modulation having acyclic prefix as guard interval. For antenna space diversity, adistributed MISO scheme is applied across the transmitters. In addition,a Peak-to-Average Power Reduction (PAPR) scheme is performed in the timedomain. For flexible network planning, this proposal provides a set ofvarious FFT sizes, guard interval lengths and corresponding pilotpatterns. Details of operations of the OFDM Generation block 1030 willbe described later.

The Signaling Generation block 1040 can create physical layer signalinginformation used for the operation of each functional block. Thissignaling information is also transmitted so that the services ofinterest are properly recovered at the receiver side. Details ofoperations of the Signaling Generation block 1040 will be describedlater.

FIGS. 2, 3 and 4 illustrate the input formatting block 1000 according toembodiments of the present invention. A description will be given ofeach figure.

FIG. 2 illustrates an input formatting block according to one embodimentof the present invention. FIG. 2 shows an input formatting module whenthe input signal is a single input stream.

The input formatting block illustrated in FIG. 2 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

The input to the physical layer may be composed of one or multiple datastreams. Each data stream is carried by one DP. The mode adaptationmodules slice the incoming data stream into data fields of the basebandframe (BBF). The system supports three types of input data streams:MPEG2-TS, Internet protocol (IP) and Generic stream (GS). MPEG2-TS ischaracterized by fixed length (188 byte) packets with the first bytebeing a sync-byte (0x47). An IP stream is composed of variable length IPdatagram packets, as signaled within IP packet headers. The systemsupports both IPv4 and IPv6 for the IP stream. GS may be composed ofvariable length packets or constant length packets, signaled withinencapsulation packet headers.

(a) shows a mode adaptation block 2000 and a stream adaptation 2010 forsignal DP and (b) shows a PLS generation block 2020 and a PLS scrambler2030 for generating and processing PLS data. A description will be givenof the operation of each block.

The Input Stream Splitter splits the input TS, IP, GS streams intomultiple service or service component (audio, video, etc.) streams. Themode adaptation module 2010 is comprised of a CRC Encoder, BB (baseband)Frame Slicer, and BB Frame Header Insertion block.

The CRC Encoder provides three kinds of CRC encoding for error detectionat the user packet (UP) level, i.e., CRC-8, CRC-16, and CRC-32. Thecomputed CRC bytes are appended after the UP. CRC-8 is used for TSstream and CRC-32 for IP stream. If the GS stream doesn't provide theCRC encoding, the proposed CRC encoding should be applied.

BB Frame Slicer maps the input into an internal logical-bit format. Thefirst received bit is defined to be the MSB. The BB Frame Slicerallocates a number of input bits equal to the available data fieldcapacity. To allocate a number of input bits equal to the BBF payload,the UP packet stream is sliced to fit the data field of BBF.

BB Frame Header Insertion block can insert fixed length BBF header of 2bytes is inserted in front of the BB Frame. The BBF header is composedof STUFFI (1 bit), SYNCD (13 bits), and RFU (2 bits). In addition to thefixed 2-Byte BBF header, BBF can have an extension field (1 or 3 bytes)at the end of the 2-byte BBF header.

The stream adaptation 2010 is comprised of stuffing insertion block andBB scrambler.

The stuffing insertion block can insert stuffing field into a payload ofa BB frame. If the input data to the stream adaptation is sufficient tofill a BB-Frame, STUFFI is set to ‘0’ and the BBF has no stuffing field.Otherwise STUFFI is set to ‘1’ and the stuffing field is insertedimmediately after the BBF header. The stuffing field comprises two bytesof the stuffing field header and a variable size of stuffing data.

The BB scrambler scrambles complete BBF for energy dispersal. Thescrambling sequence is synchronous with the BBF. The scrambling sequenceis generated by the feed-back shift register.

The PLS generation block 2020 can generate physical layer signaling(PLS) data. The PLS provides the receiver with a means to accessphysical layer DPs. The PLS data consists of PLS1 data and PLS2 data.

The PLS1 data is a first set of PLS data carried in the FSS symbols inthe frame having a fixed size, coding and modulation, which carriesbasic information about the system as well as the parameters needed todecode the PLS2 data. The PLS1 data provides basic transmissionparameters including parameters required to enable the reception anddecoding of the PLS2 data. Also, the PLS1 data remains constant for theduration of a frame-group.

The PLS2 data is a second set of PLS data transmitted in the FSS symbol,which carries more detailed PLS data about the system and the DPs. ThePLS2 contains parameters that provide sufficient information for thereceiver to decode the desired DP. The PLS2 signaling further consistsof two types of parameters, PLS2 Static data (PLS2-STAT data) and PLS2dynamic data (PLS2-DYN data). The PLS2 Static data is PLS2 data thatremains static for the duration of a frame-group and the PLS2 dynamicdata is PLS2 data that may dynamically change frame-by-frame.

Details of the PLS data will be described later.

The PLS scrambler 2030 can scramble the generated PLS data for energydispersal.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 3 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 3 shows a mode adaptation block of the input formatting block whenthe input signal corresponds to multiple input streams.

The mode adaptation block of the input formatting block for processingthe multiple input streams can independently process the multiple inputstreams.

Referring to FIG. 3, the mode adaptation block for respectivelyprocessing the multiple input streams can include an input streamsplitter 3000, an input stream synchronizer 3010, a compensating delayblock 3020, a null packet deletion block 3030, a head compression block3040, a CRC encoder 3050, a BB frame slicer 3060 and a BB headerinsertion block 3070. Description will be given of each block of themode adaptation block.

Operations of the CRC encoder 3050, BB frame slicer 3060 and BB headerinsertion block 3070 correspond to those of the CRC encoder, BB frameslicer and BB header insertion block described with reference to FIG. 2and thus description thereof is omitted.

The input stream splitter 3000 can split the input TS, IP, GS streamsinto multiple service or service component (audio, video, etc.) streams.

The input stream synchronizer 3010 may be referred as ISSY. The ISSY canprovide suitable means to guarantee Constant Bit Rate (CBR) and constantend-to-end transmission delay for any input data format. The ISSY isalways used for the case of multiple DPs carrying TS, and optionallyused for multiple DPs carrying GS streams.

The compensating delay block 3020 can delay the split TS packet streamfollowing the insertion of ISSY information to allow a TS packetrecombining mechanism without requiring additional memory in thereceiver.

The null packet deletion block 3030, is used only for the TS inputstream case. Some TS input streams or split TS streams may have a largenumber of null-packets present in order to accommodate VBR (variablebit-rate) services in a CBR TS stream. In this case, in order to avoidunnecessary transmission overhead, null-packets can be identified andnot transmitted. In the receiver, removed null-packets can bere-inserted in the exact place where they were originally by referenceto a deleted null-packet (DNP) counter that is inserted in thetransmission, thus guaranteeing constant bit-rate and avoiding the needfor time-stamp (PCR) updating.

The head compression block 3040 can provide packet header compression toincrease transmission efficiency for TS or IP input streams. Because thereceiver can have a priori information on certain parts of the header,this known information can be deleted in the transmitter.

For Transport Stream, the receiver has a-priori information about thesync-byte configuration (0x47) and the packet length (188 Byte). If theinput TS stream carries content that has only one PID, i.e., for onlyone service component (video, audio, etc.) or service sub-component (SVCbase layer, SVC enhancement layer, MVC base view or MVC dependentviews), TS packet header compression can be applied (optionally) to theTransport Stream. IP packet header compression is used optionally if theinput steam is an IP stream.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 4 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 4 illustrates a stream adaptation block of the input formattingmodule when the input signal corresponds to multiple input streams.

Referring to FIG. 4, the mode adaptation block for respectivelyprocessing the multiple input streams can include a scheduler 4000, an1-Frame delay block 4010, a stuffing insertion block 4020, an in-bandsignaling 4030, a BB Frame scrambler 4040, a PLS generation block 4050and a PLS scrambler 4060. Description will be given of each block of thestream adaptation block.

Operations of the stuffing insertion block 4020, the BB Frame scrambler4040, the PLS generation block 4050 and the PLS scrambler 4060correspond to those of the stuffing insertion block, BB scrambler, PLSgeneration block and the PLS scrambler described with reference to FIG.2 and thus description thereof is omitted.

The scheduler 4000 can determine the overall cell allocation across theentire frame from the amount of FECBLOCKs of each DP. Including theallocation for PLS, EAC and FIC, the scheduler generate the values ofPLS2-DYN data, which is transmitted as in-band signaling or PLS cell inFSS of the frame. Details of FECBLOCK, EAC and FIC will be describedlater.

The 1-Frame delay block 4010 can delay the input data by onetransmission frame such that scheduling information about the next framecan be transmitted through the current frame for in-band signalinginformation to be inserted into the DPs.

The in-band signaling 4030 can insert un-delayed part of the PLS2 datainto a DP of a frame.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 5 illustrates a BICM block according to an embodiment of thepresent invention.

The BICM block illustrated in FIG. 5 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

As described above, the apparatus for transmitting broadcast signals forfuture broadcast services according to an embodiment of the presentinvention can provide a terrestrial broadcast service, mobile broadcastservice, UHDTV service, etc.

Since QoS (quality of service) depends on characteristics of a serviceprovided by the apparatus for transmitting broadcast signals for futurebroadcast services according to an embodiment of the present invention,data corresponding to respective services needs to be processed throughdifferent schemes. Accordingly, the a BICM block according to anembodiment of the present invention can independently process DPs inputthereto by independently applying SISO, MISO and MIMO schemes to thedata pipes respectively corresponding to data paths. Consequently, theapparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can controlQoS for each service or service component transmitted through each DP.

(a) shows the BICM block shared by the base profile and the handheldprofile and (b) shows the BICM block of the advanced profile.

The BICM block shared by the base profile and the handheld profile andthe BICM block of the advanced profile can include plural processingblocks for processing each DP.

A description will be given of each processing block of the BICM blockfor the base profile and the handheld profile and the BICM block for theadvanced profile.

A processing block 5000 of the BICM block for the base profile and thehandheld profile can include a Data FEC encoder 5010, a bit interleaver5020, a constellation mapper 5030, an SSD (Signal Space Diversity)encoding block 5040 and a time interleaver 5050.

The Data FEC encoder 5010 can perform the FEC encoding on the input BBFto generate FECBLOCK procedure using outer coding (BCH), and innercoding (LDPC). The outer coding (BCH) is optional coding method. Detailsof operations of the Data FEC encoder 5010 will be described later.

The bit interleaver 5020 can interleave outputs of the Data FEC encoder5010 to achieve optimized performance with combination of the LDPC codesand modulation scheme while providing an efficiently implementablestructure. Details of operations of the bit interleaver 5020 will bedescribed later.

The constellation mapper 5030 can modulate each cell word from the bitinterleaver 5020 in the base and the handheld profiles, or cell wordfrom the Cell-word demultiplexer 5010-1 in the advanced profile usingeither QPSK, QAM-16, non-uniform QAM (NUQ-64, NUQ-256, NUQ-1024) ornon-uniform constellation (NUC-16, NUC-64, NUC-256, NUC-1024) to give apower-normalized constellation point, el. This constellation mapping isapplied only for DPs. Observe that QAM-16 and NUQs are square shaped,while NUCs have arbitrary shape. When each constellation is rotated byany multiple of 90 degrees, the rotated constellation exactly overlapswith its original one. This “rotation-sense” symmetric property makesthe capacities and the average powers of the real and imaginarycomponents equal to each other. Both NUQs and NUCs are definedspecifically for each code rate and the particular one used is signaledby the parameter DP_MOD filed in PLS2 data.

The SSD encoding block 5040 can precode cells in two (2D), three (3D),and four (4D) dimensions to increase the reception robustness underdifficult fading conditions.

The time interleaver 5050 can operates at the DP level. The parametersof time interleaving (TI) may be set differently for each DP. Details ofoperations of the time interleaver 5050 will be described later.

A processing block 5000-1 of the BICM block for the advanced profile caninclude the Data FEC encoder, bit interleaver, constellation mapper, andtime interleaver. However, the processing block 5000-1 is distinguishedfrom the processing block 5000 further includes a cell-worddemultiplexer 5010-1 and a MIMO encoding block 5020-1.

Also, the operations of the Data FEC encoder, bit interleaver,constellation mapper, and time interleaver in the processing block5000-1 correspond to those of the Data FEC encoder 5010, bit interleaver5020, constellation mapper 5030, and time interleaver 5050 described andthus description thereof is omitted.

The cell-word demultiplexer 5010-1 is used for the DP of the advancedprofile to divide the single cell-word stream into dual cell-wordstreams for MIMO processing. Details of operations of the cell-worddemultiplexer 5010-1 will be described later.

The MIMO encoding block 5020-1 can processing the output of thecell-word demultiplexer 5010-1 using MIMO encoding scheme. The MIMOencoding scheme was optimized for broadcasting signal transmission. TheMIMO technology is a promising way to get a capacity increase but itdepends on channel characteristics. Especially for broadcasting, thestrong LOS component of the channel or a difference in the receivedsignal power between two antennas caused by different signal propagationcharacteristics makes it difficult to get capacity gain from MIMO. Theproposed MIMO encoding scheme overcomes this problem using arotation-based pre-coding and phase randomization of one of the MIMOoutput signals.

MIMO encoding is intended for a 2×2 MIMO system requiring at least twoantennas at both the transmitter and the receiver. Two MIMO encodingmodes are defined in this proposal; full-rate spatial multiplexing(FR-SM) and full-rate full-diversity spatial multiplexing (FRFD-SM). TheFR-SM encoding provides capacity increase with relatively smallcomplexity increase at the receiver side while the FRFD-SM encodingprovides capacity increase and additional diversity gain with a greatcomplexity increase at the receiver side. The proposed MIMO encodingscheme has no restriction on the antenna polarity configuration.

MIMO processing is required for the advanced profile frame, which meansall DPs in the advanced profile frame are processed by the MIMO encoder.MIMO processing is applied at DP level. Pairs of the ConstellationMapper outputs NUQ (e1,i and e2,i) are fed to the input of the MIMOEncoder. Paired MIMO Encoder output (g1,i and g2,i) is transmitted bythe same carrier k and OFDM symbol l of their respective TX antennas.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention.

The BICM block illustrated in FIG. 6 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

FIG. 6 illustrates a BICM block for protection of physical layersignaling (PLS), emergency alert channel (EAC) and fast informationchannel (FIC). EAC is a part of a frame that carries EAS informationdata and FIC is a logical channel in a frame that carries the mappinginformation between a service and the corresponding base DP. Details ofthe EAC and FIC will be described later.

Referring to FIG. 6, the BICM block for protection of PLS, EAC and FICcan include a PLS FEC encoder 6000, a bit interleaver 6010, aconstellation mapper 6020 and time interleaver 6030.

Also, the PLS FEC encoder 6000 can include a scrambler, BCHencoding/zero insertion block, LDPC encoding block and LDPC paritypuncturing block. Description will be given of each block of the BICMblock.

The PLS FEC encoder 6000 can encode the scrambled PLS ½ data, EAC andFIC section.

The scrambler can scramble PLS1 data and PLS2 data before BCH encodingand shortened and punctured LDPC encoding.

The BCH encoding/zero insertion block can perform outer encoding on thescrambled PLS ½ data using the shortened BCH code for PLS protection andinsert zero bits after the BCH encoding. For PLS1 data only, the outputbits of the zero insertion may be permutted before LDPC encoding.

The LDPC encoding block can encode the output of the BCH encoding/zeroinsertion block using LDPC code. To generate a complete coded block,Cldpc, parity bits, Pldpc are encoded systematically from eachzero-inserted PLS information block, Ildpc and appended after it.

C _(ldpc) =[I _(ldpc) P _(ldpc) ]=[i ₀ ,i ₁ , . . . ,i _(K) _(ldpc) ₋₁,p ₀ ,p ₁ , . . . ,p _(N) _(ldpc) _(-K) _(ldpc) ₋₁]  [Equation 1]

The LDPC code parameters for PLS1 and PLS2 are as following table 4.

TABLE 4 Signaling Kldpc code Type Ksig Kbch Nbch_parity (=Nbch) NldpcNldpc_parity rate Qldpc PLS1 342 1020 60 1080 4320 3240 1/4 36 PLS2<1021 >1020 2100 2160 7200 5040 3/10 56

The LDPC parity puncturing block can perform puncturing on the PLS1 dataand PLS 2 data.

When shortening is applied to the PLS1 data protection, some LDPC paritybits are punctured after LDPC encoding. Also, for the PLS2 dataprotection, the LDPC parity bits of PLS2 are punctured after LDPCencoding. These punctured bits are not transmitted.

The bit interleaver 6010 can interleave the each shortened and puncturedPLS1 data and PLS2 data. The constellation mapper 6020 can map the bitinterleaved PLS1 data and PLS2 data onto constellations.

The time interleaver 6030 can interleave the mapped PLS1 data and PLS2data.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention.

The frame building block illustrated in FIG. 7 corresponds to anembodiment of the frame building block 1020 described with reference toFIG. 1.

Referring to FIG. 7, the frame building block can include a delaycompensation block 7000, a cell mapper 7010 and a frequency interleaver7020. Description will be given of each block of the frame buildingblock.

The delay compensation block 7000 can adjust the timing between the datapipes and the corresponding PLS data to ensure that they are co-timed atthe transmitter end. The PLS data is delayed by the same amount as datapipes are by addressing the delays of data pipes caused by the InputFormatting block and BICM block. The delay of the BICM block is mainlydue to the time interleaver 5050. In-band signaling data carriesinformation of the next TI group so that they are carried one frameahead of the DPs to be signaled. The Delay Compensating block delaysin-band signaling data accordingly.

The cell mapper 7010 can map PLS, EAC, FIC, DPs, auxiliary streams anddummy cells into the active carriers of the OFDM symbols in the frame.The basic function of the cell mapper 7010 is to map data cells producedby the TIs for each of the DPs, PLS cells, and EAC/FIC cells, if any,into arrays of active OFDM cells corresponding to each of the OFDMsymbols within a frame. Service signaling data (such as PSI (programspecific information)/SI) can be separately gathered and sent by a datapipe. The Cell Mapper operates according to the dynamic informationproduced by the scheduler and the configuration of the frame structure.Details of the frame will be described later.

The frequency interleaver 7020 can randomly interleave data cellsreceived from the cell mapper 7010 to provide frequency diversity. Also,the frequency interleaver 7020 can operate on very OFDM symbol paircomprised of two sequential OFDM symbols using a differentinterleaving-seed order to get maximum interleaving gain in a singleframe. Details of operations of the frequency interleaver 7020 will bedescribed later.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 8 illustrates an OFMD generation block according to an embodimentof the present invention.

The OFMD generation block illustrated in FIG. 8 corresponds to anembodiment of the OFMD generation block 1030 described with reference toFIG. 1.

The OFDM generation block modulates the OFDM carriers by the cellsproduced by the Frame Building block, inserts the pilots, and producesthe time domain signal for transmission. Also, this block subsequentlyinserts guard intervals, and applies PAPR (Peak-to-Average Power Radio)reduction processing to produce the final RF signal.

Referring to FIG. 8, the frame building block can include a pilot andreserved tone insertion block 8000, a 2D-eSFN encoding block 8010, anIFFT (Inverse Fast Fourier Transform) block 8020, a PAPR reduction block8030, a guard interval insertion block 8040, a preamble insertion block8050, other system insertion block 8060 and a DAC block 8070.Description will be given of each block of the frame building block.

The pilot and reserved tone insertion block 8000 can insert pilots andthe reserved tone.

Various cells within the OFDM symbol are modulated with referenceinformation, known as pilots, which have transmitted values known apriori in the receiver. The information of pilot cells is made up ofscattered pilots (SP), continual pilots (CP), edge pilots (EP), FSS(frame signaling symbol) pilots and FES (frame edge symbol) pilots. Eachpilot is transmitted at a particular boosted power level according topilot type and pilot pattern. The value of the pilot information isderived from a reference sequence, which is a series of values, one foreach transmitted carrier on any given symbol. The pilots can be used forframe synchronization, frequency synchronization, time synchronization,channel estimation, and transmission mode identification, and also canbe used to follow the phase noise.

Reference information, taken from the reference sequence, is transmittedin scattered pilot cells in every symbol except the preamble, FSS andFES of the frame. Continual pilots are inserted in every symbol of theframe. The number and location of continual pilots depends on both theFFT size and the scattered pilot pattern. The edge carriers are edgepilots in every symbol except for the preamble symbol. They are insertedin order to allow frequency interpolation up to the edge of thespectrum. FSS pilots are inserted in FSS(s) and FES pilots are insertedin FES. They are inserted in order to allow time interpolation up to theedge of the frame.

The system according to an embodiment of the present invention supportsthe SFN network, where distributed MISO scheme is optionally used tosupport very robust transmission mode. The 2D-eSFN is a distributed MISOscheme that uses multiple TX antennas, each of which is located in thedifferent transmitter site in the SFN network.

The 2D-eSFN encoding block 8010 can process a 2D-eSFN processing todistorts the phase of the signals transmitted from multipletransmitters, in order to create both time and frequency diversity inthe SFN configuration. Hence, burst errors due to low flat fading ordeep-fading for a long time can be mitigated.

The IFFT block 8020 can modulate the output from the 2D-eSFN encodingblock 8010 using OFDM modulation scheme. Any cell in the data symbolswhich has not been designated as a pilot (or as a reserved tone) carriesone of the data cells from the frequency interleaver. The cells aremapped to OFDM carriers.

The PAPR reduction block 8030 can perform a PAPR reduction on inputsignal using various PAPR reduction algorithm in the time domain.

The guard interval insertion block 8040 can insert guard intervals andthe preamble insertion block 8050 can insert preamble in front of thesignal. Details of a structure of the preamble will be described later.The other system insertion block 8060 can multiplex signals of aplurality of broadcast transmission/reception systems in the time domainsuch that data of two or more different broadcast transmission/receptionsystems providing broadcast services can be simultaneously transmittedin the same RF signal bandwidth. In this case, the two or more differentbroadcast transmission/reception systems refer to systems providingdifferent broadcast services. The different broadcast services may referto a terrestrial broadcast service, mobile broadcast service, etc. Datarelated to respective broadcast services can be transmitted throughdifferent frames.

The DAC block 8070 can convert an input digital signal into an analogsignal and output the analog signal. The signal output from the DACblock 7800 can be transmitted through multiple output antennas accordingto the physical layer profiles. A Tx antenna according to an embodimentof the present invention can have vertical or horizontal polarity.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention cancorrespond to the apparatus for transmitting broadcast signals forfuture broadcast services, described with reference to FIG. 1.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention can includea synchronization & demodulation module 9000, a frame parsing module9010, a demapping & decoding module 9020, an output processor 9030 and asignaling decoding module 9040. A description will be given of operationof each module of the apparatus for receiving broadcast signals.

The synchronization & demodulation module 9000 can receive input signalsthrough m Rx antennas, perform signal detection and synchronization withrespect to a system corresponding to the apparatus for receivingbroadcast signals and carry out demodulation corresponding to a reverseprocedure of the procedure performed by the apparatus for transmittingbroadcast signals.

The frame parsing module 9010 can parse input signal frames and extractdata through which a service selected by a user is transmitted. If theapparatus for transmitting broadcast signals performs interleaving, theframe parsing module 9010 can carry out deinterleaving corresponding toa reverse procedure of interleaving. In this case, the positions of asignal and data that need to be extracted can be obtained by decodingdata output from the signaling decoding module 9400 to restorescheduling information generated by the apparatus for transmittingbroadcast signals.

The demapping & decoding module 9020 can convert the input signals intobit domain data and then deinterleave the same as necessary. Thedemapping & decoding module 9200 can perform demapping for mappingapplied for transmission efficiency and correct an error generated on atransmission channel through decoding. In this case, the demapping &decoding module 9020 can obtain transmission parameters necessary fordemapping and decoding by decoding the data output from the signalingdecoding module 9040.

The output processor 9030 can perform reverse procedures of variouscompression/signal processing procedures which are applied by theapparatus for transmitting broadcast signals to improve transmissionefficiency. In this case, the output processor 9030 can acquirenecessary control information from data output from the signalingdecoding module 9040. The output of the output processor 9030corresponds to a signal input to the apparatus for transmittingbroadcast signals and may be MPEG-TSs, IP streams (v4 or v6) and genericstreams.

The signaling decoding module 9040 can obtain PLS information from thesignal demodulated by the synchronization & demodulation module 9000. Asdescribed above, the frame parsing module 9010, demapping & decodingmodule 9020 and output processor 9030 can execute functions thereofusing the data output from the signaling decoding module 9040.

FIG. 10 illustrates a frame structure according to an embodiment of thepresent invention.

FIG. 10 shows an example configuration of the frame types and FRUs in asuper-frame. (a) shows a super frame according to an embodiment of thepresent invention, (b) shows FRU (Frame Repetition Unit) according to anembodiment of the present invention, (c) shows frames of variable PHYprofiles in the FRU and (d) shows a structure of a frame.

A super-frame may be composed of eight FRUs. The FRU is a basicmultiplexing unit for TDM of the frames, and is repeated eight times ina super-frame.

Each frame in the FRU belongs to one of the PHY profiles, (base,handheld, advanced) or FEF. The maximum allowed number of the frames inthe FRU is four and a given PHY profile can appear any number of timesfrom zero times to four times in the FRU (e.g., base, base, handheld,advanced). PHY profile definitions can be extended using reserved valuesof the PHY_PROFILE in the preamble, if required.

The FEF part is inserted at the end of the FRU, if included. When theFEF is included in the FRU, the minimum number of FEFs is 8 in asuper-frame. It is not recommended that FEF parts be adjacent to eachother.

One frame is further divided into a number of OFDM symbols and apreamble. As shown in (d), the frame comprises a preamble, one or moreframe signaling symbols (FSS), normal data symbols and a frame edgesymbol (FES).

The preamble is a special symbol that enables fast Futurecast UTB systemsignal detection and provides a set of basic transmission parameters forefficient transmission and reception of the signal. The detaileddescription of the preamble will be will be described later.

The main purpose of the FSS(s) is to carry the PLS data. For fastsynchronization and channel estimation, and hence fast decoding of PLSdata, the FSS has more dense pilot pattern than the normal data symbol.The FES has exactly the same pilots as the FSS, which enablesfrequency-only interpolation within the FES and temporal interpolation,without extrapolation, for symbols immediately preceding the FES.

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention.

FIG. 11 illustrates the signaling hierarchy structure, which is splitinto three main parts: the preamble signaling data 11000, the PLS1 data11010 and the PLS2 data 11020. The purpose of the preamble, which iscarried by the preamble symbol in every frame, is to indicate thetransmission type and basic transmission parameters of that frame. ThePLS1 enables the receiver to access and decode the PLS2 data, whichcontains the parameters to access the DP of interest. The PLS2 iscarried in every frame and split into two main parts: PLS2-STAT data andPLS2-DYN data. The static and dynamic portion of PLS2 data is followedby padding, if necessary.

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention.

Preamble signaling data carries 21 bits of information that are neededto enable the receiver to access PLS data and trace DPs within the framestructure. Details of the preamble signaling data are as follows:

PHY_PROFILE: This 3-bit field indicates the PHY profile type of thecurrent frame. The mapping of different PHY profile types is given inbelow table 5.

TABLE 5 Value PHY profile 000 Base profile 001 Handheld profile 010Advanced profiled 011~110 Reserved 111 FEF

FFT_SIZE: This 2 bit field indicates the FFT size of the current framewithin a frame-group, as described in below table 6.

TABLE 6 Value FFT size 00 8K FFT 01 16K FFT 10 32K FFT 11 Reserved

GI_FRACTION: This 3 bit field indicates the guard interval fractionvalue in the current super-frame, as described in below table 7.

TABLE 7 Value GI_FRACTION 000 ⅕ 001 1/10 010 1/20 011 1/40 100 1/80 1011/160 110~111 Reserved

EAC_FLAG: This 1 bit field indicates whether the EAC is provided in thecurrent frame. If this field is set to ‘1’, emergency alert service(EAS) is provided in the current frame. If this field set to ‘0’, EAS isnot carried in the current frame. This field can be switched dynamicallywithin a super-frame.

PILOT_MODE: This 1-bit field indicates whether the pilot mode is mobilemode or fixed mode for the current frame in the current frame-group. Ifthis field is set to ‘0’, mobile pilot mode is used. If the field is setto ‘1’, the fixed pilot mode is used.

PAPR_FLAG: This 1-bit field indicates whether PAPR reduction is used forthe current frame in the current frame-group. If this field is set tovalue ‘1’, tone reservation is used for PAPR reduction. If this field isset to ‘0’, PAPR reduction is not used.

FRU_CONFIGURE: This 3-bit field indicates the PHY profile typeconfigurations of the frame repetition units (FRU) that are present inthe current super-frame. All profile types conveyed in the currentsuper-frame are identified in this field in all preambles in the currentsuper-frame. The 3-bit field has a different definition for eachprofile, as show in below table 8.

TABLE 8 Current Current Current Current PHY_PROFILE = PHY_PROFILE =PHY_PROFILE = PHY_PROFILE = ‘000’ ‘001’ ‘010’ ‘111’ (base) (handheld)(advanced) (FEF) FRU_CONFIGURE = Only base Only Only Only FEF 000profile handheld advanced present present profile profile presentpresent FRU_CONFIGURE = Handheld Base Base Base 1XX profile profileprofile profile present present present present FRU_CONFIGURE = AdvancedAdvanced Handheld Handheld X1X profile profile profile profile presentpresent present present FRU_CONFIGURE = FEF FEF FEF Advanced XX1 presentpresent present profile present

RESERVED: This 7-bit field is reserved for future use.

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention.

PLS1 data provides basic transmission parameters including parametersrequired to enable the reception and decoding of the PLS2. As abovementioned, the PLS1 data remain unchanged for the entire duration of oneframe-group. The detailed definition of the signaling fields of the PLS1data are as follows:

PREAMBLE_DATA: This 20-bit field is a copy of the preamble signalingdata excluding the EAC_FLAG.

NUM_FRAME_FRU: This 2-bit field indicates the number of the frames perFRU.

PAYLOAD_TYPE: This 3-bit field indicates the format of the payload datacarried in the frame-group. PAYLOAD_TYPE is signaled as shown in table9.

TABLE 9 Value Payload type 1XX TS stream is transmitted X1X IP stream istransmitted XX1 GS stream is transmitted

NUM_FSS: This 2-bit field indicates the number of FSS symbols in thecurrent frame.

SYSTEM_VERSION: This 8-bit field indicates the version of thetransmitted signal format. The SYSTEM_VERSION is divided into two 4-bitfields, which are a major version and a minor version.

Major version: The MSB four bits of SYSTEM_VERSION field indicate majorversion information. A change in the major version field indicates anon-backward-compatible change. The default value is ‘0000’. For theversion described in this standard, the value is set to ‘0000’.

Minor version: The LSB four bits of SYSTEM_VERSION field indicate minorversion information. A change in the minor version field isbackward-compatible.

CELL_ID: This is a 16-bit field which uniquely identifies a geographiccell in an ATSC network. An ATSC cell coverage area may consist of oneor more frequencies, depending on the number of frequencies used perFuturecast UTB system. If the value of the CELL_ID is not known orunspecified, this field is set to ‘0’.

NETWORK_ID: This is a 16-bit field which uniquely identifies the currentATSC network.

SYSTEM_ID: This 16-bit field uniquely identifies the Futurecast UTBsystem within the ATSC network. The Futurecast UTB system is theterrestrial broadcast system whose input is one or more input streams(TS, IP, GS) and whose output is an RF signal. The Futurecast UTB systemcarries one or more PHY profiles and FEF, if any. The same FuturecastUTB system may carry different input streams and use different RFfrequencies in different geographical areas, allowing local serviceinsertion. The frame structure and scheduling is controlled in one placeand is identical for all transmissions within a Futurecast UTB system.One or more Futurecast UTB systems may have the same SYSTEM_ID meaningthat they all have the same physical layer structure and configuration.

The following loop consists of FRU_PHY_PROFILE, FRU_FRAME_LENGTH,FRU_GI_FRACTION, and RESERVED which are used to indicate the FRUconfiguration and the length of each frame type. The loop size is fixedso that four PHY profiles (including a FEF) are signaled within the FRU.If NUM_FRAME_FRU is less than 4, the unused fields are filled withzeros.

FRU_PHY_PROFILE: This 3-bit field indicates the PHY profile type of the(i+1)th (i is the loop index) frame of the associated FRU. This fielduses the same signaling format as shown in the table 8.

FRU_FRAME_LENGTH: This 2-bit field indicates the length of the (i+1)thframe of the associated FRU. Using FRU_FRAME_LENGTH together withFRU_GI_FRACTION, the exact value of the frame duration can be obtained.

FRU_GI_FRACTION: This 3-bit field indicates the guard interval fractionvalue of the (i+1)th frame of the associated FRU. FRU_GI_FRACTION issignaled according to the table 7.

RESERVED: This 4-bit field is reserved for future use.

The following fields provide parameters for decoding the PLS2 data.

PLS2_FEC_TYPE: This 2-bit field indicates the FEC type used by the PLS2protection. The FEC type is signaled according to table 10. The detailsof the LDPC codes will be described later.

TABLE 10 Contents PLS2 FEC type 00 4K-1/4 and 7K-3/10 LDPC codes 01~11Reserved

PLS2_MOD: This 3-bit field indicates the modulation type used by thePLS2. The modulation type is signaled according to table 11.

TABLE 11 Value PLS2_MODE 000 BPSK 001 QPSK 010 QAM-16 011 NUQ-64 100~111Reserved

PLS2_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block, thesize (specified as the number of QAM cells) of the collection of fullcoded blocks for PLS2 that is carried in the current frame-group. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_STAT_SIZE_BIT: This 14-bit field indicates the size, in bits, ofthe PLS2-STAT for the current frame-group. This value is constant duringthe entire duration of the current frame-group.

PLS2_DYN_SIZE_BIT: This 14-bit field indicates the size, in bits, of thePLS2-DYN for the current frame-group. This value is constant during theentire duration of the current frame-group.

PLS2_REP_FLAG: This 1-bit flag indicates whether the PLS2 repetitionmode is used in the current frame-group. When this field is set to value‘1’, the PLS2 repetition mode is activated. When this field is set tovalue ‘0’, the PLS2 repetition mode is deactivated.

PLS2_REP_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block,the size (specified as the number of QAM cells) of the collection ofpartial coded blocks for PLS2 carried in every frame of the currentframe-group, when PLS2 repetition is used. If repetition is not used,the value of this field is equal to 0. This value is constant during theentire duration of the current frame-group.

PLS2_NEXT_FEC_TYPE: This 2-bit field indicates the FEC type used forPLS2 that is carried in every frame of the next frame-group. The FECtype is signaled according to the table 10.

PLS2_NEXT_MOD: This 3-bit field indicates the modulation type used forPLS2 that is carried in every frame of the next frame-group. Themodulation type is signaled according to the table 11.

PLS2_NEXT_REP_FLAG: This 1-bit flag indicates whether the PLS2repetition mode is used in the next frame-group. When this field is setto value ‘1’, the PLS2 repetition mode is activated. When this field isset to value ‘0’, the PLS2 repetition mode is deactivated.

PLS2_NEXT_REP_SIZE_CELL: This 15-bit field indicates Ctotal_full_block,The size (specified as the number of QAM cells) of the collection offull coded blocks for PLS2 that is carried in every frame of the nextframe-group, when PLS2 repetition is used. If repetition is not used inthe next frame-group, the value of this field is equal to 0. This valueis constant during the entire duration of the current frame-group.

PLS2_NEXT_REP_STAT_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-STAT for the next frame-group. This value is constantin the current frame-group.

PLS2_NEXT_REP_DYN_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-DYN for the next frame-group. This value is constantin the current frame-group.

PLS2_AP_MODE: This 2-bit field indicates whether additional parity isprovided for PLS2 in the current frame-group. This value is constantduring the entire duration of the current frame-group. The below table12 gives the values of this field. When this field is set to ‘00’,additional parity is not used for the PLS2 in the current frame-group.

TABLE 12 Value PLS2-AP mode 00 AP is not provided 01 AP1 mode 10~11Reserved

PLS2_AP_SIZE_CELL: This 15-bit field indicates the size (specified asthe number of QAM cells) of the additional parity bits of the PLS2. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_NEXT_AP_MODE: This 2-bit field indicates whether additional parityis provided for PLS2 signaling in every frame of next frame-group. Thisvalue is constant during the entire duration of the current frame-group.The table 12 defines the values of this field

PLS2_NEXT_AP_SIZE_CELL: This 15-bit field indicates the size (specifiedas the number of QAM cells) of the additional parity bits of the PLS2 inevery frame of the next frame-group. This value is constant during theentire duration of the current frame-group.

RESERVED: This 32-bit field is reserved for future use.

CRC_32: A 32-bit error detection code, which is applied to the entirePLS1 signaling.

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention.

FIG. 14 illustrates PLS2-STAT data of the PLS2 data. The PLS2-STAT dataare the same within a frame-group, while the PLS2-DYN data provideinformation that is specific for the current frame.

The details of fields of the PLS2-STAT data are as follows:

FIC_FLAG: This 1-bit field indicates whether the FIC is used in thecurrent frame-group. If this field is set to ‘1’, the FIC is provided inthe current frame. If this field set to ‘0’, the FIC is not carried inthe current frame. This value is constant during the entire duration ofthe current frame-group.

AUX_FLAG: This 1-bit field indicates whether the auxiliary stream(s) isused in the current frame-group. If this field is set to ‘1’, theauxiliary stream is provided in the current frame. If this field set to‘0’, the auxiliary stream is not carried in the current frame. Thisvalue is constant during the entire duration of current frame-group.

NUM_DP: This 6-bit field indicates the number of DPs carried within thecurrent frame. The value of this field ranges from 1 to 64, and thenumber of DPs is NUM_DP+1.

DP_ID: This 6-bit field identifies uniquely a DP within a PHY profile.

DP_TYPE: This 3-bit field indicates the type of the DP. This is signaledaccording to the below table 13.

TABLE 13 Value DP Type 000 DP Type 1 001 DP Type 2 010~111 reserved

DP_GROUP_ID: This 8-bit field identifies the DP group with which thecurrent DP is associated. This can be used by a receiver to access theDPs of the service components associated with a particular service,which will have the same DP_GROUP_ID.

BASE_DP_ID: This 6-bit field indicates the DP carrying service signalingdata (such as PSI/SI) used in the Management layer. The DP indicated byBASE_DP_ID may be either a normal DP carrying the service signaling dataalong with the service data or a dedicated DP carrying only the servicesignaling data

DP_FEC_TYPE: This 2-bit field indicates the FEC type used by theassociated DP. The FEC type is signaled according to the below table 14.

TABLE 14 Value FEC_TYPE 00 16K LDPC 01 64K LDPC 10~11 Reserved

DP_COD: This 4-bit field indicates the code rate used by the associatedDP. The code rate is signaled according to the below table 15.

TABLE 15 Value Code rate 0000 5/15 0001 6/15 0010 7/15 0011 8/15 01009/15 0101 10/15  0110 11/15  0111 12/15  1000 13/15  1001~1111 Reserved

DP_MOD: This 4-bit field indicates the modulation used by the associatedDP. The modulation is signaled according to the below table 16.

TABLE 16 Value Modulation 0000 QPSK 0001 QAM-16 0010 NUQ-64 0011 NUQ-2560100 NUQ-1024 0101 NUC-16 0110 NUC-64 0111 NUC-256 1000 NUC-10241001~1111 reserved

DP_SSD_FLAG: This 1-bit field indicates whether the SSD mode is used inthe associated DP. If this field is set to value ‘1’, SSD is used. Ifthis field is set to value ‘0’, SSD is not used.

The following field appears only if PHY_PROFILE is equal to ‘010’, whichindicates the advanced profile:

DP_MIMO: This 3-bit field indicates which type of MIMO encoding processis applied to the associated DP. The type of MIMO encoding process issignaled according to the table 17.

TABLE 17 Value MIMO encoding 000 FR-SM 001 FRFD-SM 010~111 reserved

DP_TI_TYPE: This 1-bit field indicates the type of time-interleaving. Avalue of ‘0’ indicates that one TI group corresponds to one frame andcontains one or more TI-blocks. A value of ‘1’ indicates that one TIgroup is carried in more than one frame and contains only one TI-block.

DP_TI_LENGTH: The use of this 2-bit field (the allowed values are only1, 2, 4, 8) is determined by the values set within the DP_TI_TYPE fieldas follows:

If the DP_TI_TYPE is set to the value ‘1’, this field indicates PI, thenumber of the frames to which each TI group is mapped, and there is oneTI-block per TI group (NTI=1). The allowed PI values with 2-bit fieldare defined in the below table 18.

If the DP_TI_TYPE is set to the value ‘0’, this field indicates thenumber of TI-blocks NTI per TI group, and there is one TI group perframe (Pi=1). The allowed PI values with 2-bit field are defined in thebelow table 18.

TABLE 18 2-bit field PI NTI 00 1 1 01 2 2 10 4 3 11 8 4

DP_FRAME_INTERVAL: This 2-bit field indicates the frame interval (IJUMP)within the frame-group for the associated DP and the allowed values are1, 2, 4, 8 (the corresponding 2-bit field is ‘00’, ‘01’, ‘10’, or ‘11’,respectively). For DPs that do not appear every frame of theframe-group, the value of this field is equal to the interval betweensuccessive frames. For example, if a DP appears on the frames 1, 5, 9,13, etc., this field is set to ‘4’. For DPs that appear in every frame,this field is set to ‘1’.

DP_TI_BYPASS: This 1-bit field determines the availability of timeinterleaver 5050. If time interleaving is not used for a DP, it is setto ‘1’. Whereas if time interleaving is used it is set to ‘0’.

DP_FIRST_FRAME_IDX: This 5-bit field indicates the index of the firstframe of the super-frame in which the current DP occurs. The value ofDP_FIRST_FRAME_IDX ranges from 0 to 31

DP_NUM_BLOCK_MAX: This 10-bit field indicates the maximum value ofDP_NUM_BLOCKS for this DP. The value of this field has the same range asDP_NUM_BLOCKS.

DP_PAYLOAD_TYPE: This 2-bit field indicates the type of the payload datacarried by the given DP. DP_PAYLOAD_TYPE is signaled according to thebelow table 19.

TABLE 19 Value Payload Type 00 TS. 01 IP 10 GS 11 reserved

DP_INBAND_MODE: This 2-bit field indicates whether the current DPcarries in-band signaling information. The in-band signaling type issignaled according to the below table 20.

TABLE 20 Value In-band mode 00 In-band signaling is not carried. 01INBAND-PLS is carried only 10 INBAND-ISSY is carried only 11 INBAND-PLSand INBAND-ISSY are carried

DP_PROTOCOL_TYPE: This 2-bit field indicates the protocol type of thepayload carried by the given DP. It is signaled according to the belowtable 21 when input payload types are selected.

TABLE 21 If If If DP_PAYLOAD_TYPE DP_PAYLOAD_TYPE DP_PAYLOAD_TYPE ValueIs TS Is IP Is GS 00 MPEG2-TS IPv4 (Note) 01 Reserved IPv6 Reserved 10Reserved Reserved Reserved 11 Reserved Reserved Reserved

DP_CRC_MODE: This 2-bit field indicates whether CRC encoding is used inthe Input Formatting block. The CRC mode is signaled according to thebelow table 22.

TABLE 22 Value CRC mode 00 Not used 01 CRC-8 10 CRC-16 11 CRC-32

DNP_MODE: This 2-bit field indicates the null-packet deletion mode usedby the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). DNP_MODEis signaled according to the below table 23. If DP_PAYLOAD_TYPE is notTS (‘00’), DNP_MODE is set to the value ‘00’.

TABLE 23 Value Null-packet deletion mode 00 Not used 01 DNP-NORMAL 10DNP-OFFSET 11 reserved

ISSY_MODE: This 2-bit field indicates the ISSY mode used by theassociated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). The ISSY_MODE issignaled according to the below table 24 If DP_PAYLOAD_TYPE is not TS(‘00’), ISSY_MODE is set to the value ‘00’.

TABLE 24 Value ISSY mode 00 Not used 01 ISSY-UP 10 ISSY-BBF 11 reserved

HC_MODE_TS: This 2-bit field indicates the TS header compression modeused by the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). TheHC_MODE_TS is signaled according to the below table 25.

TABLE 25 Value Header compression mode 00 HC_MODE_TS 1 01 HC_MODE_TS 210 HC_MODE_TS 3 11 HC_MODE_TS 4

HC_MODE_IP: This 2-bit field indicates the IP header compression modewhen DP_PAYLOAD_TYPE is set to IP (‘01’). The HC_MODE_IP is signaledaccording to the below table 26.

TABLE 26 Value Header compression mode 00 No compression 01 HC_MODE_IP 110~11 reserved

PID: This 13-bit field indicates the PID number for TS headercompression when DP_PAYLOAD_TYPE is set to TS (‘00’) and HC_MODE_TS isset to ‘01’ or ‘10’.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if FIC_FLAG is equal to ‘1’:

FIC_VERSION: This 8-bit field indicates the version number of the FIC.

FIC_LENGTH_BYTE: This 13-bit field indicates the length, in bytes, ofthe FIC.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if AUX_FLAG is equal to ‘1’:

NUM_AUX: This 4-bit field indicates the number of auxiliary streams.Zero means no auxiliary streams are used.

AUX_CONFIG_RFU: This 8-bit field is reserved for future use.

AUX_STREAM_TYPE: This 4-bit is reserved for future use for indicatingthe type of the current auxiliary stream.

AUX_PRIVATE_CONFIG: This 28-bit field is reserved for future use forsignaling auxiliary streams.

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention.

FIG. 15 illustrates PLS2-DYN data of the PLS2 data. The values of thePLS2-DYN data may change during the duration of one frame-group, whilethe size of fields remains constant.

The details of fields of the PLS2-DYN data are as follows:

FRAME_INDEX: This 5-bit field indicates the frame index of the currentframe within the super-frame. The index of the first frame of thesuper-frame is set to ‘0’.

PLS_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration will change. The nextsuper-frame with changes in the configuration is indicated by the valuesignaled within this field. If this field is set to the value ‘0000’, itmeans that no scheduled change is foreseen: e.g., value ‘1’ indicatesthat there is a change in the next super-frame.

FIC_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration (i.e., the contents of theFIC) will change. The next super-frame with changes in the configurationis indicated by the value signaled within this field. If this field isset to the value ‘0000’, it means that no scheduled change is foreseen:e.g. value ‘0001’ indicates that there is a change in the nextsuper-frame.

RESERVED: This 16-bit field is reserved for future use.

The following fields appear in the loop over NUM_DP, which describe theparameters associated with the DP carried in the current frame.

DP_ID: This 6-bit field indicates uniquely the DP within a PHY profile.

DP_START: This 15-bit (or 13-bit) field indicates the start position ofthe first of the DPs using the DPU addressing scheme. The DP_START fieldhas differing length according to the PHY profile and FFT size as shownin the below table 27.

TABLE 27 DP_START field size PHY profile 64K 16K Base 13 bits 15 bitsHandheld — 13 bits Advanced 13 bits 15 bits

DP_NUM_BLOCK: This 10-bit field indicates the number of FEC blocks inthe current TI group for the current DP. The value of DP_NUM_BLOCKranges from 0 to 1023

RESERVED: This 8-bit field is reserved for future use.

The following fields indicate the FIC parameters associated with theEAC.

EAC_FLAG: This 1-bit field indicates the existence of the EAC in thecurrent frame. This bit is the same value as the EAC_FLAG in thepreamble.

EAS_WAKE_UP_VERSION_NUM: This 8-bit field indicates the version numberof a wake-up indication.

If the EAC_FLAG field is equal to ‘1’, the following bits are allocatedfor EAC_LENGTH_BYTE field. If the EAC_FLAG field is equal to ‘0’, thefollowing 12 bits are allocated for EAC_COUNTER.

EAC_LENGTH_BYTE: This 12-bit field indicates the length, in byte, of theEAC.

EAC_COUNTER: This 12-bit field indicates the number of the frames beforethe frame where the EAC arrives.

The following field appears only if the AUX_FLAG field is equal to ‘1’:

AUX_PRIVATE_DYN: This 48-bit field is reserved for future use forsignaling auxiliary streams. The meaning of this field depends on thevalue of AUX_STREAM_TYPE in the configurable PLS2-STAT.

CRC_32: A 32-bit error detection code, which is applied to the entirePLS2.

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention.

As above mentioned, the PLS, EAC, FIC, DPs, auxiliary streams and dummycells are mapped into the active carriers of the OFDM symbols in theframe. The PLS1 and PLS2 are first mapped into one or more FSS(s). Afterthat, EAC cells, if any, are mapped immediately following the PLS field,followed next by FIC cells, if any. The DPs are mapped next after thePLS or EAC, FIC, if any. Type 1 DPs follows first, and Type 2 DPs next.The details of a type of the DP will be described later. In some case,DPs may carry some special data for EAS or service signaling data. Theauxiliary stream or streams, if any, follow the DPs, which in turn arefollowed by dummy cells. Mapping them all together in the abovementioned order, i.e. PLS, EAC, FIC, DPs, auxiliary streams and dummydata cells exactly fill the cell capacity in the frame.

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention.

PLS cells are mapped to the active carriers of FSS(s). Depending on thenumber of cells occupied by PLS, one or more symbols are designated asFSS(s), and the number of FSS(s) N_FSS is signaled by NUM_FSS in PLS1.The FSS is a special symbol for carrying PLS cells. Since robustness andlatency are critical issues in the PLS, the FSS(s) has higher density ofpilots allowing fast synchronization and frequency-only interpolationwithin the FSS.

PLS cells are mapped to active carriers of the NFSS FSS(s) in a top-downmanner as shown in an example in FIG. 17. The PLS1 cells are mappedfirst from the first cell of the first FSS in an increasing order of thecell index. The PLS2 cells follow immediately after the last cell of thePLS1 and mapping continues downward until the last cell index of thefirst FSS. If the total number of required PLS cells exceeds the numberof active carriers of one FSS, mapping proceeds to the next FSS andcontinues in exactly the same manner as the first FSS.

After PLS mapping is completed, DPs are carried next. If EAC, FIC orboth are present in the current frame, they are placed between PLS and“normal” DPs.

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention.

EAC is a dedicated channel for carrying EAS messages and links to theDPs for EAS. EAS support is provided but EAC itself may or may not bepresent in every frame. EAC, if any, is mapped immediately after thePLS2 cells. EAC is not preceded by any of the FIC, DPs, auxiliarystreams or dummy cells other than the PLS cells. The procedure ofmapping the EAC cells is exactly the same as that of the PLS.

The EAC cells are mapped from the next cell of the PLS2 in increasingorder of the cell index as shown in the example in FIG. 18. Depending onthe EAS message size, EAC cells may occupy a few symbols, as shown inFIG. 18.

EAC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required EAC cells exceeds the number of remainingactive carriers of the last FSS mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol, which has more activecarriers than a FSS.

After EAC mapping is completed, the FIC is carried next, if any exists.If FIC is not transmitted (as signaled in the PLS2 field), DPs followimmediately after the last cell of the EAC.

FIG. 19 illustrates FIC mapping according to an embodiment of thepresent invention.

(a) shows an example mapping of FIC cell without EAC and (b) shows anexample mapping of FIC cell with EAC.

FIC is a dedicated channel for carrying cross-layer information toenable fast service acquisition and channel scanning. This informationprimarily includes channel binding information between DPs and theservices of each broadcaster. For fast scan, a receiver can decode FICand obtain information such as broadcaster ID, number of services, andBASE_DP_ID. For fast service acquisition, in addition to FIC, base DPcan be decoded using BASE_DP_ID. Other than the content it carries, abase DP is encoded and mapped to a frame in exactly the same way as anormal DP. Therefore, no additional description is required for a baseDP. The FIC data is generated and consumed in the Management Layer. Thecontent of FIC data is as described in the Management Layerspecification.

The FIC data is optional and the use of FIC is signaled by the FIC_FLAGparameter in the static part of the PLS2. If FIC is used, FIC_FLAG isset to ‘1’ and the signaling field for FIC is defined in the static partof PLS2. Signaled in this field are FIC_VERSION, and FIC_LENGTH_BYTE.FIC uses the same modulation, coding and time interleaving parameters asPLS2. FIC shares the same signaling parameters such as PLS2_MOD andPLS2_FEC. FIC data, if any, is mapped immediately after PLS2 or EAC ifany. FIC is not preceded by any normal DPs, auxiliary streams or dummycells. The method of mapping FIC cells is exactly the same as that ofEAC which is again the same as PLS.

Without EAC after PLS, FIC cells are mapped from the next cell of thePLS2 in an increasing order of the cell index as shown in an example in(a). Depending on the FIC data size, FIC cells may be mapped over a fewsymbols, as shown in (b).

FIC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required FIC cells exceeds the number of remainingactive carriers of the last FSS, mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol which has more activecarriers than a FSS.

If EAS messages are transmitted in the current frame, EAC precedes FIC,and FIC cells are mapped from the next cell of the EAC in an increasingorder of the cell index as shown in (b).

After FIC mapping is completed, one or more DPs are mapped, followed byauxiliary streams, if any, and dummy cells.

FIG. 20 illustrates a type of DP according to an embodiment of thepresent invention.

shows type 1 DP and (b) shows type 2 DP.

After the preceding channels, i.e., PLS, EAC and FIC, are mapped, cellsof the DPs are mapped. A DP is categorized into one of two typesaccording to mapping method:

Type 1 DP: DP is mapped by TDM

Type 2 DP: DP is mapped by FDM

The type of DP is indicated by DP_TYPE field in the static part of PLS2.FIG. 20 illustrates the mapping orders of Type 1 DPs and Type 2 DPs.Type 1 DPs are first mapped in the increasing order of cell index, andthen after reaching the last cell index, the symbol index is increasedby one. Within the next symbol, the DP continues to be mapped in theincreasing order of cell index starting from p=0. With a number of DPsmapped together in one frame, each of the Type 1 DPs are grouped intime, similar to TDM multiplexing of DPs.

Type 2 DPs are first mapped in the increasing order of symbol index, andthen after reaching the last OFDM symbol of the frame, the cell indexincreases by one and the symbol index rolls back to the first availablesymbol and then increases from that symbol index. After mapping a numberof DPs together in one frame, each of the Type 2 DPs are grouped infrequency together, similar to FDM multiplexing of DPs.

Type 1 DPs and Type 2 DPs can coexist in a frame if needed with onerestriction; Type 1 DPs always precede Type 2 DPs. The total number ofOFDM cells carrying Type 1 and Type 2 DPs cannot exceed the total numberof OFDM cells available for transmission of DPs:

D _(DP1) +D _(DP2) ≦D _(DP)  [Equation 2]

where DDP1 is the number of OFDM cells occupied by Type 1 DPs, DDP2 isthe number of cells occupied by Type 2 DPs. Since PLS, EAC, FIC are allmapped in the same way as Type 1 DP, they all follow “Type 1 mappingrule”. Hence, overall, Type 1 mapping always precedes Type 2 mapping.

FIG. 21 illustrates DP mapping according to an embodiment of the presentinvention.

shows an addressing of OFDM cells for mapping type 1 DPs and (b) showsan addressing of OFDM cells for mapping for type 2 DPs.

Addressing of OFDM cells for mapping Type 1 DPs (0, . . . , DDP1−1) isdefined for the active data cells of Type 1 DPs. The addressing schemedefines the order in which the cells from the TIs for each of the Type 1DPs are allocated to the active data cells. It is also used to signalthe locations of the DPs in the dynamic part of the PLS2.

Without EAC and FIC, address 0 refers to the cell immediately followingthe last cell carrying PLS in the last FSS. If EAC is transmitted andFIC is not in the corresponding frame, address 0 refers to the cellimmediately following the last cell carrying EAC. If FIC is transmittedin the corresponding frame, address 0 refers to the cell immediatelyfollowing the last cell carrying FIC. Address 0 for Type 1 DPs can becalculated considering two different cases as shown in (a). In theexample in (a), PLS, EAC and FIC are assumed to be all transmitted.Extension to the cases where either or both of EAC and FIC are omittedis straightforward. If there are remaining cells in the FSS aftermapping all the cells up to FIC as shown on the left side of (a).

Addressing of OFDM cells for mapping Type 2 DPs (0, . . . , DDP2−1) isdefined for the active data cells of Type 2 DPs. The addressing schemedefines the order in which the cells from the TIs for each of the Type 2DPs are allocated to the active data cells. It is also used to signalthe locations of the DPs in the dynamic part of the PLS2.

Three slightly different cases are possible as shown in (b). For thefirst case shown on the left side of (b), cells in the last FSS areavailable for Type 2 DP mapping. For the second case shown in themiddle, FIC occupies cells of a normal symbol, but the number of FICcells on that symbol is not larger than CFSS. The third case, shown onthe right side in (b), is the same as the second case except that thenumber of FIC cells mapped on that symbol exceeds CFSS.

The extension to the case where Type 1 DP(s) precede Type 2 DP(s) isstraightforward since PLS, EAC and FIC follow the same “Type 1 mappingrule” as the Type 1 DP(s).

A data pipe unit (DPU) is a basic unit for allocating data cells to a DPin a frame.

A DPU is defined as a signaling unit for locating DPs in a frame. A CellMapper 7010 may map the cells produced by the TIs for each of the DPs. ATime interleaver 5050 outputs a series of TI-blocks and each TI-blockcomprises a variable number of XFECBLOCKs which is in turn composed of aset of cells. The number of cells in an XFECBLOCK, Ncells, is dependenton the FECBLOCK size, Nldpc, and the number of transmitted bits perconstellation symbol. A DPU is defined as the greatest common divisor ofall possible values of the number of cells in a XFECBLOCK, Ncells,supported in a given PHY profile. The length of a DPU in cells isdefined as LDPU. Since each PHY profile supports different combinationsof FECBLOCK size and a different number of bits per constellationsymbol, LDPU is defined on a PHY profile basis.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention before bit interleaving. As above mentioned, Data FECencoder may perform the FEC encoding on the input BBF to generateFECBLOCK procedure using outer coding (BCH), and inner coding (LDPC).The illustrated FEC structure corresponds to the FECBLOCK. Also, theFECBLOCK and the FEC structure have same value corresponding to a lengthof LDPC codeword.

The BCH encoding is applied to each BBF (Kbch bits), and then LDPCencoding is applied to BCH-encoded BBF (Kldpc bits=Nbch bits) asillustrated in FIG. 22.

The value of Nldpc is either 64800 bits (long FECBLOCK) or 16200 bits(short FECBLOCK).

The below table 28 and table 29 show FEC encoding parameters for a longFECBLOCK and a short FECBLOCK, respectively.

TABLE 28 BCH error correction LDPC Rate Nldpc Kldpc Kbch capability Nbch− Kbch 5/15 64800 21600 21408 12 192 6/15 25920 25728 7/15 30240 300488/15 34560 34368 9/15 38880 38688 10/15  43200 43008 11/15  47520 4732812/15  51840 51648 13/15  56160 55968

TABLE 29 BCH error correction LDPC Rate Nldpc Kldpc Kbch capability Nbch− Kbch 5/15 16200 5400 5232 12 168 6/15 6480 6312 7/15 7560 7392 8/158640 8472 9/15 9720 9552 10/15  10800 10632 11/15  11880 11712 12/15 12960 12792 13/15  14040 13872

The details of operations of the BCH encoding and LDPC encoding are asfollows:

A 12-error correcting BCH code is used for outer encoding of the BBF.The BCH generator polynomial for short FECBLOCK and long FECBLOCK areobtained by multiplying together all polynomials.

LDPC code is used to encode the output of the outer BCH encoding. Togenerate a completed Bldpc (FECBLOCK), Pldpc (parity bits) is encodedsystematically from each Ildpc (BCH-encoded BBF), and appended to Ildpc.The completed Bldpc (FECBLOCK) are expressed as follow Equation.

B _(ldpc) =[I _(ldpc) P _(ldpc) ]=[i ₀ ,i ₁ , . . . ,i _(K) _(ldpc) ₋₁,p ₀ ,p ₁ , . . . ,p _(N) _(ldpc) _(-K) _(ldpc) ₋₁]  [Equation 3]

The parameters for long FECBLOCK and short FECBLOCK are given in theabove table 28 and 29, respectively.

The detailed procedure to calculate Nldpc−Kldpc parity bits for longFECBLOCK, is as follows:

1) Initialize the parity bits,

p ₀ =p ₁ =p ₂ = . . . =p _(N) _(ldpc) _(-K) _(ldpc) ₋₁=0  [Equation 4]

2) Accumulate the first information bit—i0, at parity bit addressesspecified in the first row of an addresses of parity check matrix. Thedetails of addresses of parity check matrix will be described later. Forexample, for rate 13/15:

p ₉₈₃ =p ₉₈₃ ⊕i ₀ p ₂₈₁₅ =p ₂₈₁₅ ⊕i ₀

p ₄₈₃₇ =p ₄₈₃₇ ⊕i ₀ p ₄₉₈₉ =p ₄₉₈₉ ⊕i ₀

p ₆₁₈₃ =p ₆₁₈₃ ⊕i ₀ p ₆₄₅₈ =p ₆₄₅₈ ⊕i ₀

p ₆₉₂₁ =p ₆₉₂₁ ⊕i ₀ p ₆₉₇₄ =p ₆₉₇₄ ⊕i ₀

p ₇₅₇₂ =p ₇₅₇₂ ⊕i ₀ p ₈₂₆₀ =p ₈₂₆₀ ⊕i ₀

p ₈₄₉₆ =p ₈₄₉₆ ⊕i ₀  [Equation 5]

3) For the next 359 information bits, is, s=1, 2, . . . , 359 accumulateis at parity bit addresses using following Equation.

{x+(s mod 360)×Q _(ldpc)} mod(N _(ldpc) −K _(ldpc))  [Equation 6]

where x denotes the address of the parity bit accumulator correspondingto the first bit i0, and Qldpc is a code rate dependent constantspecified in the addresses of parity check matrix. Continuing with theexample, Qldpc=24 for rate 13/15, so for information bit i1, thefollowing operations are performed:

p ₁₀₀₇ =p ₁₀₀₇ ⊕i ₁ p ₂₈₃₉ =p ₂₈₃₉ ⊕i ₁

p ₄₈₆₁ =p ₄₈₆₁ ⊕i ₁ p ₅₀₁₃ =p ₅₀₁₃ ⊕i ₁

p ₆₁₆₂ =p ₆₁₆₂ ⊕i ₁ p ₆₄₈₂ =p ₆₄₈₂ ⊕i ₁

p ₆₉₄₅ =p ₆₉₄₅ ⊕i ₁ p ₆₉₉₈ =p ₆₉₉₈ ⊕i ₁

p ₇₅₉₆ =p ₇₅₉₆ ⊕i ₁ p ₈₂₈₄ =p ₈₂₈₄ ⊕i ₁

p ₈₅₂₀ =p ₈₅₂₀ ⊕i ₁  [Equation 7]

4) For the 361st information bit i360, the addresses of the parity bitaccumulators are given in the second row of the addresses of paritycheck matrix. In a similar manner the addresses of the parity bitaccumulators for the following 359 information bits is, s=361, 362, . .. , 719 are obtained using the Equation 6, where x denotes the addressof the parity bit accumulator corresponding to the information bit i360,i.e., the entries in the second row of the addresses of parity checkmatrix.

5) In a similar manner, for every group of 360 new information bits, anew row from addresses of parity check matrixes used to find theaddresses of the parity bit accumulators.

After all of the information bits are exhausted, the final parity bitsare obtained as follows:

6) Sequentially perform the following operations starting with i=1

p _(i) =p _(i) ⊕p _(i-1) , i=1,2, . . . ,N _(ldpc) −K_(ldpc)−1  [Equation 8]

where final content of pi, i=0, 1, . . . Nldpc−Kldpc−1 is equal to theparity bit pi.

TABLE 30 Code Rate Qldpc 5/15 120 6/15 108 7/15 96 8/15 84 9/15 7210/15  60 11/15  48 12/15  36 13/15  24

This LDPC encoding procedure for a short FECBLOCK is in accordance witht LDPC encoding procedure for the long FECBLOCK, except replacing thetable 30 with table 31, and replacing the addresses of parity checkmatrix for the long FECBLOCK with the addresses of parity check matrixfor the short FECBLOCK.

TABLE 31 Code Rate Qldpc 5/15 30 6/15 27 7/15 24 8/15 21 9/15 18 10/15 15 11/15  12 12/15  9 13/15  6

FIG. 23 illustrates a bit interleaving according to an embodiment of thepresent invention.

The outputs of the LDPC encoder are bit-interleaved, which consists ofparity interleaving followed by Quasi-Cyclic Block (QCB) interleavingand inner-group interleaving.

shows Quasi-Cyclic Block (QCB) interleaving and (b) shows inner-groupinterleaving.

The FECBLOCK may be parity interleaved. At the output of the parityinterleaving, the LDPC codeword consists of 180 adjacent QC blocks in along FECBLOCK and 45 adjacent QC blocks in a short FECBLOCK. Each QCblock in either a long or short FECBLOCK consists of 360 bits. Theparity interleaved LDPC codeword is interleaved by QCB interleaving. Theunit of QCB interleaving is a QC block. The QC blocks at the output ofparity interleaving are permutated by QCB interleaving as illustrated inFIG. 23, where Ncells=64800/η mod or 16200/η mod according to theFECBLOCK length. The QCB interleaving pattern is unique to eachcombination of modulation type and LDPC code rate.

After QCB interleaving, inner-group interleaving is performed accordingto modulation type and order (η mod) which is defined in the below table32. The number of QC blocks for one inner-group, NQCB_IG, is alsodefined.

TABLE 32 Modulation type ηmod NQCB_IG QAM-16 4 2 NUC-16 4 4 NUQ-64 6 3NUC-64 6 6 NUQ-256 8 4 NUC-256 8 8 NUQ-1024 10 5 NUC-1024 10 10

The inner-group interleaving process is performed with NQCB_IG QC blocksof the QCB interleaving output. Inner-group interleaving has a processof writing and reading the bits of the inner-group using 360 columns andNQCB_IG rows. In the write operation, the bits from the QCB interleavingoutput are written row-wise. The read operation is performed column-wiseto read out m bits from each row, where m is equal to 1 for NUC and 2for NUQ.

FIG. 24 illustrates a cell-word demultiplexing according to anembodiment of the present invention.

shows a cell-word demultiplexing for 8 and 12 bpcu MIMO and (b) shows acell-word demultiplexing for 10 bpcu MIMO.

Each cell word (c0,l, c1,l, . . . , cη mod−1,l) of the bit interleavingoutput is demultiplexed into (d1,0,m, d1,1,m . . . , d1,η mod−1,m) and(d2,0,m, d2,1,m . . . , d2,η mod−1,m) as shown in (a), which describesthe cell-word demultiplexing process for one XFECBLOCK.

For the 10 bpcu MIMO case using different types of NUQ for MIMOencoding, the Bit Interleaver for NUQ-1024 is re-used. Each cell word(c0,l, c1,l, . . . , c9,l) of the Bit Interleaver output isdemultiplexed into (d1,0,m, d1,1,m . . . , d1, 3,m) and (d2,0,m, d2,1,m. . . , d2,5,m), as shown in (b).

FIG. 25 illustrates a time interleaving according to an embodiment ofthe present invention.

(a) to (c) show examples of TI mode.

The time interleaver operates at the DP level. The parameters of timeinterleaving (TI) may be set differently for each DP.

The following parameters, which appear in part of the PLS2-STAT data,configure the TI:

DP_TI_TYPE (allowed values: 0 or 1): Represents the TI mode; ‘0’indicates the mode with multiple TI blocks (more than one TI block) perTI group. In this case, one TI group is directly mapped to one frame (nointer-frame interleaving). ‘1’ indicates the mode with only one TI blockper TI group. In this case, the TI block may be spread over more thanone frame (inter-frame interleaving).

DP_TI_LENGTH: If DP_TI_TYPE=‘0’, this parameter is the number of TIblocks Nil per TI group. For DP_TI_TYPE=‘1’, this parameter is thenumber of frames PI spread from one TI group.

DP_NUM_BLOCK_MAX (allowed values: 0 to 1023): Represents the maximumnumber of XFECBLOCKs per TI group.

DP_FRAME_INTERVAL (allowed values: 1, 2, 4, 8): Represents the number ofthe frames IJUMP between two successive frames carrying the same DP of agiven PHY profile.

DP_TI_BYPASS (allowed values: 0 or 1): If time interleaving is not usedfor a DP, this parameter is set to ‘1’. It is set to ‘0’ if timeinterleaving is used.

Additionally, the parameter DP_NUM_BLOCK from the PLS2-DYN data is usedto represent the number of XFECBLOCKs carried by one TI group of the DP.

When time interleaving is not used for a DP, the following TI group,time interleaving operation, and TI mode are not considered. However,the Delay Compensation block for the dynamic configuration informationfrom the scheduler will still be required. In each DP, the XFECBLOCKsreceived from the SSD/MIMO encoding are grouped into TI groups. That is,each TI group is a set of an integer number of XFECBLOCKs and willcontain a dynamically variable number of XFECBLOCKs. The number ofXFECBLOCKs in the TI group of index n is denoted by NxBLOCK_Group(n) andis signaled as DP_NUM_BLOCK in the PLS2-DYN data. Note thatNxBLOCK_Group(n) may vary from the minimum value of 0 to the maximumvalue NxBLOCK_Group_MAX (corresponding to DP_NUM_BLOCK_MAX) of which thelargest value is 1023.

Each TI group is either mapped directly onto one frame or spread over PIframes. Each TI group is also divided into more than one TI blocks(NTI), where each TI block corresponds to one usage of time interleavermemory. The TI blocks within the TI group may contain slightly differentnumbers of XFECBLOCKs. If the TI group is divided into multiple TIblocks, it is directly mapped to only one frame. There are three optionsfor time interleaving (except the extra option of skipping the timeinterleaving) as shown in the below table 33.

TABLE 33 Mode Description Option-1 Each TI group contains one TI blockand is mapped directly to one frame as shown in (a). This option issignaled in the PLS2-STAT by DP_TI_TYPE = ‘0’ and DP_TI_LENGTH = ‘1’(N_(TI) = 1). Option-2 Each TI group contains one TI block and is mappedto more than one frame. (b) shows an example, where one TI group ismapped to two frames, i.e., DP_TI_LENGTH = ‘2’ (P_(I) = 2) andDP_FRAME_INTERVAL (I_(JUMP) = 2). This provides greater time diversityfor low data-rate services. This option is signaled in the PLS2-STAT byDP_TI_TYPE = ‘1’. Option-3 Each TI group is divided into multiple TIblocks and is mapped directly to one frame as shown in (c). Each TIblock may use full TI memory, so as to provide the maximum bit-rate fora DP. This option is signaled in the PLS2-STAT signaling by DP_TI_TYPE =‘0’ and DP_TI_LENGTH = NTI, while P_(I) = 1.

In each DP, the TI memory stores the input XFECBLOCKs (output XFECBLOCKsfrom the SSD/MIMO encoding block). Assume that input XFECBLOCKs aredefined as

(d _(n,s,0,0) ,d _(n,s,0,1) , . . . , d _(n,s,O,N) _(cells) ⁻¹ , d_(n,s,1,0) , . . . , d _(n,s,1,N) _(cells) ⁻¹ , . . . , d _(n,s,N)_(xBLOCK_TI) _((n,s)−1.0) , . . . d _(n,s,N) _(xBLOCK_TI) _((n,s)−1,N)_(cells) ⁻¹)

where d_(n,s,r,q) is the qth cell of the rth XFECBLOCK in the sth TIblock of the nth TI group and represents the outputs of SSD and MIMOencodings as follows

$d_{n,s,r,q} = \left\{ {\begin{matrix}{f_{n,s,r,q},} & {{the}\mspace{14mu} {output}\mspace{14mu} {of}\mspace{14mu} {SSD}\mspace{14mu} \cdots \mspace{14mu} {encoding}} \\{g_{n,s,r,q},} & {{the}\mspace{14mu} {output}\mspace{14mu} {of}\mspace{14mu} {MIMO}\mspace{14mu} {encoding}}\end{matrix}.} \right.$

In addition, assume that output XFECBLOCKs from the time interleaver5050 are defined as

(h _(n,s,0) , h _(n,s,1) , . . . , h _(n,s,i) , . . . , h _(n,s,N)_(xBLOCK_TI) _((n,s)×N) _(cells) ⁻¹)

where h_(n,s,i) is the ith output cell (for i=0, . . . , N_(xBLOCK) _(_)_(TI)(n,s)×N_(cells)−1) in the sth TI block of the nth TI group.

Typically, the time interleaver will also act as a buffer for DP dataprior to the process of frame building. This is achieved by means of twomemory banks for each DP. The first TI-block is written to the firstbank. The second TI-block is written to the second bank while the firstbank is being read from and so on.

The TI is a twisted row-column block interleaver. For the sth TI blockof the nth TI group, the number of rows N_(r) of a TI memory is equal tothe number of cells N_(cells), i.e., N_(r)=N_(cells) while the number ofcolumns N_(c) is equal to the number N_(xBLOCK) _(_) _(TI)(n,s).

FIG. 26 illustrates a basic operation of a twisted row-column blockinterleaver according to an exemplary embodiment of the presentinvention.

FIG. 26A illustrates a writing operation in a time interleaver and FIG.26B illustrates a reading operation in the time interleaver. Asillustrated in FIG. 26A, a first XFECBLOCK is written in a first columnof a time interleaving memory in a column direction and a secondXFECBLOCK is written in a next column, and such an operation iscontinued. In addition, in an interleaving array, a cell is read in adiagonal direction. As illustrated in FIG. 26B, while the diagonalreading is in progress from a first row (to a right side along the rowstarting from a leftmost column) to a last row, N_(r) cells are read. Indetail, when it is assumed that z_(n,s,i)(i=0, . . . , N_(r)N_(c)) is atime interleaving memory cell position to be sequentially read, thereading operation in the interleaving array is executed by calculating arow index R_(n,s,i), a column index C_(n,s,i), and associated twistparameter T_(n,s,i) as shown in an equation given below.

[Equation 9]   GENERATE (R_(n,s,i), C_(n,s,i))=   { R_(n,s,i) = mod(i,N_(r)), T_(n,s,i) = mod(S_(shift) × R_(n,s,i), N_(c)),$C_{n,s,i} = {{mod}\left( {{T_{n,s,i} + \left\lfloor \frac{i}{N_{r}} \right\rfloor},N_{c}} \right)}$}

Where, S_(shift) is a common shift value for a diagonal reading processregardless of N_(xBLOCK) _(_) _(TI)(n,s) and the shift value is decidedby N_(xBLOCK) _(_) _(TI) _(_) _(MAX) given in PLS2-STAT as shown in anequation given below.

$\begin{matrix}{{for}\left\{ {\begin{matrix}\begin{matrix}{N_{{{xBLOCK}\_ {TI}}{\_ {MAX}}}^{\prime} =} \\{{N_{{{xBLOCK}\_ {TI}}{\_ {MAX}}} + 1},}\end{matrix} & {{{{if}\mspace{14mu} N_{{{xBLOCK}\_ {TI}}{\_ {MAX}}}\; {mod}\; 2} = 0}\;} \\\begin{matrix}{N_{{xBLOCK}\mspace{14mu} {TI}\mspace{14mu} {MAX}}^{\prime} =} \\{N_{{xBLOCK}\mspace{14mu} {TI}\mspace{14mu} {MAX}},}\end{matrix} & {{{{if}\mspace{14mu} N_{{xBLOCK}\mspace{14mu} {TI}\mspace{14mu} {MAX}}{mod}\; 2} = 1}\;}\end{matrix},\mspace{20mu} {S_{shift} = \frac{N_{{{xBLOCK}\_ {TI}}{\_ {MAX}}}^{\prime} - 1}{2}}} \right.} & \left\lbrack {{Equation}\mspace{14mu} 10} \right\rbrack\end{matrix}$

Consequently, the cell position to be read is calculated by a coordinatez_(n,s,i)=N_(r)C_(n,s,i)+R_(n,s,i).

FIG. 27 illustrates an operation of a twisted row-column blockinterleaver according to another exemplary embodiment of the presentinvention.

In more detail, FIG. 27 illustrates an interleaving array in the timeinterleaving memory for respective time interleaving groups including avirtual XFECBLOCK when N_(xBLOCK) _(_) _(TI)(0,0)=3, N_(xBLOCK) _(_)_(TI)(1,0)=6, and N_(xBLOCK) _(_) _(TI)(2,0)=5.

A variable N_(xBLOCK) _(_) _(TI)(n,s)=N_(r) will be equal to or smallerthan N′_(xBLOCK) _(_) _(TI) _(_) _(MAX). Accordingly, in order for areceiver to achieve single memory interleaving regardless of N_(xBLOCK)_(_) _(TI)(n,s), the size of the interleaving array for the twistedrow-column block interleaver is set to a size ofN_(r)×N_(c)=N_(cells)×N′_(xBLOCK) _(_) _(TI) _(_) _(MAX) by insertingthe virtual XFECBLOCK into the time interleaving memory and a readingprocess is achieved as shown in an equation given below.

[Equation 11] p = 0; for i = 0; i < N_(cells)N_(xBLOCK) _(—) _(TI) _(—)_(MAX)′; i = i + 1 {GENERATE (R_(n,s,i), C_(n,s,i)); V_(i) =N_(r)C_(n,s,j) + R_(n,s,j)  if V_(i) < N_(cells)N_(xBLOCK TI) (n,s)  {  Z_(n,s,p) = V_(i); p = p + 1;   } }

The number of the time interleaving groups is set to 3. An option of thetime interleaver is signaled in the PLS2-STAT by DP_TI_TYPE=‘0’,DP_FRAME_INTERVAL=‘1’, and DP_TI_LENGTH=‘1’, that is, NTI=1, IJUMP=1,and PI=1. The number of respective XFECBLOCKs per time interleavinggroup, of which Ncells=30 is signaled in PLS2-DYN data byNxBLOCK_TI(0,0)=3, NxBLOCK_TI(1,0)=6, and NxBLOCK_TI(2,0)=5 of therespective XFECBLOCKs. The maximum number of XFECBLOCKs is signaled inthe PLS2-STAT data by NxBLOCK_Group_MAX and this is continued to└N_(xBLOCK) _(_) _(Group) _(_) _(MAX)/N_(TI)┘=N_(xBLOCK) _(_) _(TI) _(_)_(MAX)=6.

FIG. 28 illustrates a diagonal reading pattern of the twisted row-columnblock interleaver according to the exemplary embodiment of the presentinvention.

In more detail, FIG. 28 illustrates a diagonal reading pattern fromrespective interleaving arrays having parameters N′_(xBLOCK) _(_) _(TI)_(_) _(MAX)=7 and Sshift=(7−1)/2=3. In this case, during a readingprocess expressed by a pseudo code given above, whenV_(i)≧N_(cells)N_(xBLOCK) _(_) _(TI)(n,s), a value of Vi is omitted anda next calculation value of Vi is used.

FIG. 29 illustrates XFECBLOCK interleaved from each interleaving arrayaccording to an exemplary embodiment of the present invention.

FIG. 29 illustrates XFECBLOCK interleaved from each interleaving arrayhaving parameters N′_(xBLOCK) _(_) _(TI) _(_) _(MAX)=7 and Sshift=3according to an exemplary embodiment of the present invention.

In this specification, the DP may also be called a Physical Layer Pipe(PLP), and the PLS information may also be designated as Layer 1 (L1)information or L1 signaling information. The PLS1 information may alsobe designated Layer 1 (L1) basic information, and the PLS2 informationmay also be designated as L1 detail information. In this specification,if specific information/data is signaled, it may mean that theinformation/data is transmitted and received through the L1 signalinginformation.

FIG. 30 shows the configuration of a broadcast signal transmitteraccording to another embodiment of the present invention.

The broadcast signal transmitter of FIG. 30 may include an inputformatting block 30010, a Bit Interleaved and Coded Modulation (BICM)block 30020, a framing & interleaving block 30030, and a waveformgeneration block 30040. The framing & interleaving block 30030 of FIG.30 may correspond to the frame building block of FIG. 1, and thewaveform generation block 30040 thereof may correspond to the OFDMgeneration block of FIG. 1.

FIG. 30 corresponds to a case where the frame building block 1020includes the time interleaving block 30050 unlike in the aforementionedembodiments. Accordingly, the frame building block 1020 may be calledthe framing & interleaving block 30050. In other words, the framing &interleaving block 30030 may further include a time interleaving block30050, a framing block 30060, and a frequency interleaving block 30070.The framing & interleaving block 30030 may time-interleave data usingsuch sub-blocks, may generate a signal frame by mapping the data, andmay frequency-interleave the signal frame.

The remaining description other than a case where the time interleavingblock 30050 has moved from the BICM block 30020 to the framing &interleaving block 30030 is the same as that described above. Thewaveform generation block 30040 is the same as the OFDM generation block1030 of FIG. 1 and is different in name only.

On the broadcast signal receiver side, as described above, the timeinterleaving block has moved from the demapping and decoding block 9020of FIG. 9 to the frame parsing block 9010, and the frame parsing block9010 may also be called a frame parsing/deinterleaving block. The frameparsing block 9010 may performs frequency deinterleaving, frame parsing,and time interleaving on a received signal.

In FIG. 30, only the inclusion relationships between the sub-blocks ofthe system are changed and the sub-blocks are renamed, and detailedoperations of the sub-blocks are the same as those described above. Inthis specification, as in the previous embodiments, the elements of thetransmission and reception system may also be designated blocks,modules, or units.

In FIG. 30, the framing module 31060 generates a signal frame. A methodof configuring a signal frame according to an embodiment of the presentinvention is described in more detail below.

FIG. 31 shows the structure of a signal frame according to an embodimentof the present invention.

The signal frame may include a bootstrap, a preamble, and a data part.

A bootstrap signal may be robustly designed in such a way as to operatein a poor channel environment. The bootstrap signal may carry essentialsystem information and essential information capable of accessing acorresponding broadcast system.

The bootstrap signal may be used in the locking and offset estimation ofan RF carrier frequency and the locking and offset estimation of asampling frequency. The bootstrap signal may signal system bandwidthinformation (e.g., 6, 7, 8 MHz). Furthermore, the bootstrap signal mayinclude core system signaling information (e.g., major/minor versioninformation). Furthermore, the bootstrap information may signal the timeuntil the start of a next data frame. Furthermore, the bootstrapinformation may send the identifiers of L1 signaling informationtransmitted in the preamble. Furthermore, the bootstrap signal maysupport an Emergency Alert System (EAS) wakeup function. The EAS wakeupinformation of the bootstrap signal may indicate whether an emergencysituation has occurred. That is, the EAS information may indicatewhether emergency alert information from an EAS or another source ispresent in at least one frame.

The bootstrap includes preamble structure information. The preamblestructure information may indicate L1 basic mode information,information about the FFT size of the preamble, information about the GIlength of the preamble, and information about the pilot pattern Dx ofthe preamble.

FIG. 32 shows the structure of a signal frame according to an embodimentof the present invention.

FIG. 32 shows the signal frame of FIG. 31 by symbol unit. Each of thepreamble and data of the signal frame may include at least one symbol.

The preamble conveys L1 signaling information. Furthermore, the preamblemay include a single OFDM symbol or a plurality of OFDM symbolsdepending on the size of the L1 signaling information, that is, thenumber of bits. The preamble may have the same structure as the datasymbol or may have a different structure (e.g., an FFT size and a GuardInterval (GI)) from the structure of the data symbol. In this case, thestructure of the preamble symbol or the data symbol may be signaled inthe bootstrap. That is, the bootstrap may also indicate an FFT size, GIlength, and pilot pattern of the preamble.

Advantages if information about the preamble/data part is transmitted inthe bootstrap are as follows. The operation of the broadcast signalreceiver can be simplified. Furthermore, a service acquisition timeincluding a channel scan can be reduced because the time taken to obtainL1 signaling information is reduced. Furthermore, reception performancecan be improved because an FFT/GI false detection possibility is reducedin a poor channel situation.

A single signal frame may include at least one subframe. Furthermore,one of 8K, 16K, and 32K may be used as the FFT size of each subframe,and the FFT size of each subframe may be the same or different. Thesubframe has a fixed/constant FFT size, GI length, Scattered Pilot (SP)pattern, and Number Of useful Carriers (NoC) for the correspondingsubframe. Furthermore, FFT size information, GI length information,pilot pattern information, and NoC information about a correspondingsubframe may be included in a preamble and transmitted/received.

FIG. 33 shows the pilot structure of a signal frame according to anembodiment of the present invention.

As in FIG. 33, the actual bandwidth of a signal frame may be changeddepending on the Number of Carriers (NoC).

The signal frame includes Edge Pilots (EPs), Continual Pilots (CPs), andScattered Pilots (SPs).

The EP or edge carrier indicates carriers whose carrier index kcorresponds to 0 or NoC−1.

The CP is inserted into every the symbols of the signal frame. Thefrequency direction index of the CP is determined to be a specificpattern depending on an FFT size. The CP includes a common CP and anadditional CP. The common CP corresponds to a non-SP-bearing-CP, and theadditional CP corresponds to an SP-bearing-CP. The additional CP isadded in order to regularly maintain a constant number of data carriersper data symbol. That is, the additional CP is added in order to ensurethe constant Number of Active carriers (NoA) per symbol.

A Scattered Pilot (SP) is disposed depending on an SP pattern indicatedby Dx and Dy. Dx indicates the distance or separation of a pilot-bearingcarrier in a frequency direction. Dy indicates the number of symbolsforming a single SP sequence in a time direction. For example, in FIG.33, an SP pattern is Dx=4 and Dy=4. An SP pattern used in a subframe maybe transmitted using the L1 signaling information of a preamble.

A method of boosting power of an SP is described below.

The broadcast signal transmitter may insert a pilot into a signal frameusing a pilot insertion module. The pilot insertion module maycorrespond to the pilot and tone insertion module 8000 of FIG. 8. Thepilot signal may also be used for the synchronization, channelestimation, transmission mode identification, and phase noise estimationof a received signal. Accordingly, in order to improve signal receptionand decoding performance, the power level of a pilot signal may beboosted.

A transmission and reception system can improve the entire systemperformance by improving channel estimation quality using a boostedpilot signal. If power of a pilot signal is boosted, however, theallocated power/energy of the remaining data part may be reduced becausetotal power or energy which may be used in a signal frame is limited.Accordingly, excessive power allocation for a pilot may cause todeteriorate performance due to a reduction in the power of the datapart. Accordingly, a boosting power level having optimum performance foreach SP pattern may be determined.

$\begin{matrix}{{SNR}_{EQ} = {\frac{\sigma_{S}^{2}}{\sigma_{N}^{2} + {\sigma_{N}^{2} \times f_{int}}} = {{SNR} \times \frac{1}{1 + f_{int}}}}} & \left\lbrack {{Equation}\mspace{14mu} 12} \right\rbrack\end{matrix}$

Equation 12 is an equation for modeling an equalized data SNR.

In Equation 12, (σ_s)̂2 denotes data power, (σ_N)̂2 denotes noise power,(σ_CE)̂2 denotes channel estimation false power, and f_int denotes anoise reduction factor (f<1) according to interpolation.

SNR_EQ denotes a ratio of noise versus signal power upon channelestimation, and SNR_EQ may be represented using the SNR of a receivedsignal.

$\begin{matrix}{{SNR}_{{EQ},b} = {\frac{\sigma_{s}^{2} \times k}{\sigma_{N}^{2} + {\sigma_{N}^{2} \times {f_{int}/b}}} = {{SNR} \times \frac{k}{1 + {f_{int}/b}}}}} & \left\lbrack {{Equation}\mspace{14mu} 13} \right\rbrack \\{{{SNR}_{{EQ},b}/{SNR}} = {\frac{s}{\left( {s - 1} \right) + b} \times \frac{1}{1 + {f_{int}/b}}}} & \left\lbrack {{Equation}\mspace{14mu} 14} \right\rbrack\end{matrix}$

Equation 13 is an equation for modeling an equalized data SNR if SPboosting is used.

In Equation 13, b denotes an SP boosting factor ((σ_p)̂2=b*(σ_s)̂2), kdenotes a power normalization factor (k=s/((s−1)+b)), and s denotes anSP coefficient (S=Dx*Dy). (σ_p)̂2 denotes power of an SP.

Equation 13 may be changed to Equation 14 if it is represented by aratio of an SNR if boosting is used and the SNR of a received signal.

An equalized data SNR may be optimized with respect to each SP pattern.In the modeling equations, a noise reduction factor f_int is an unknownparameter. A noise reduction may be achieved by the time and frequencyinterleaver. That is, f_int=f_int,time*f_int,freq. For example, if Dy=4,f_int,time may be 0.6875. If Dy=2, f_int,time may be 0.75. In this case,f_int,freq may be different depending on a receiver and/or a receptionenvironment. For example, f_int,freq may be 1, or f_int,freq may be 0.5.Accordingly, f_int,freq capable of optimizing processing performance ofa received signal may be determined, and a pilot boosting level may bedetermined based on the determined “f_int,freq.”

f_int may be selected depending on various use cases, a channelcondition, and/or the implementation of a receiver. Accordingly, aplurality of boosting levels can be proposed, and flexibility inselecting SP boosting power according to a system can be provided byallocating a signaling bit indicating information about a boostinglevel. In an embodiment, the boosting level may be transmitted in 2 bitsor 3 bits. A signaling parameter indicating such a boosting level mayalso be designated an SP boosting parameter or SP boosting information.

In an embodiment, regarding the SP boosting parameter, each of fivelevels may be indicated using 3 bits as follows. The five levels mayalso be designated as boosting degrees of 0˜4. Parameter values of“000”˜“100” may correspond to the respective boosting degrees of 0˜4.

“000”: SP boosting not used.

“001”: f_int,freq=0.25

“010”: f_int,freq=0.5

“011”: f_int,freq=0.75

“100”: f_int,freq=1.0

“101”˜“111”: reserved

FIGS. 34 and 35 show SP boosting information according to an embodimentof the present invention.

FIG. 34 is a table in which the SP boosting levels are indicated in dB,and FIG. 35 is a table in which the SP boosting levels are indicated inthe amplitude of normalized data carrier power. That is, in FIG. 34, apower ratio prior to boosting is 0. In FIG. 35, a power level prior toboosting is 1.

For example, if an SP pattern is SP3_4, that is, if Dx=3 and Dy=4, if aboosting level is 2(“010”) in FIG. 34, an SP pilot is boosted in 2.9 dB,and thus has amplitude of 1.40. In SP boosting information, boostedamplitude of an SP for each SP pattern may be indicated in dB or byamplitude using a parameter of 3 bits.

The SP boosting information indicates an SP boosting level according toan SP pattern using five levels (0, 1, 2, 3, and 4). One level (e.g., 0)of the five levels includes a case where boosting is not performed. Thatis, in a level of 0, amplitude of an SP becomes 0 dB or amplitude of 1.In other words, the SP boosting information indicates amplitude of anSP.

The broadcast signal transmitter and the broadcast signal receiver maystore SP boosting tables, such as FIGS. 34 and 35, and may signal onlyan SP boosting parameter, that is, SP boosting information, using 3bits.

A pilot is also inserted into the preamble of a signal frame. In anembodiment, the broadcast signal transmitter may also boost a preamblepilot. If time interpolation is not present, f_int,time may be set to1.0. Furthermore, f_int,freq may be set to have a maximum HuardUtilization Ratio (GUR) depending on the FFT size, GI length, and pilotpattern of a preamble.

In the case of a preamble pilot, a pilot pattern of Dy=1 may be used. Apreamble carries L1 signaling information and a receiver is able toprocess a received signal when L1 signaling information and the L1signaling information is fast decoded. Accordingly, for the purpose ofrapid and accurate channel estimation and sync tracking, a preamblesymbol can increase pilot density compared to a data symbol. To thisend, with respect to a preamble symbol, a pilot pattern having Dy=1 maybe used. Accordingly, if the number of preamble symbols is plural, apilot may occur at the same position of the respective preamble symbols.The Dx value of a preamble pilot may be signaled through preamblestructure information of a bootstrap.

FIGS. 36 and 37 show preamble pilot boosting information according to anembodiment of the present invention.

FIG. 36 shows boosting levels according to an FFT size, GI length, andSP Dx by GUR. The GUR may be determined using a ratio of Dx and a GI asa factor.

FIG. 37 shows the pilot boosting levels of a preamble symbol in dB unitand by amplitude unit. As in FIG. 36, FIG. 37 shows a method of boostinga preamble pilot with respect to each of 17 types according to an FFTsize, GI length, and SP Dx.

As described above, the structure of a preamble symbol is signaledthrough the preamble structure information of a bootstrap. Accordingly,the pilot boosting information of a preamble may be determined using thepreamble structure information of the bootstrap. The broadcast signaltransmitter and the broadcast signal receiver may share the data ofFIGS. 36 and 37. The broadcast signal receiver may obtain informationabout the FFT size, GI length, and SP DX of a received preamble usingthe preamble structure information of a bootstrap. Furthermore, thebroadcast signal receiver may determine a power boosting level appliedto the preamble pilot of a received signal through FIGS. 36 and 37 andmay process the received signal based on the determined power boostinglevel.

In another embodiment, SP power boosting may also be performed on aframe boundary symbol. At least one of the first symbol and last symbolof a frame or subframe may become a frame boundary symbol or an subframeboundary symbol (SBS). Pilots having greater pilot density are insertedinto an SBS compared to a data symbol. The subframe boundary pilot maybe inserted by Dx unit (Dy=1). Since a large number of pilots areinserted, energy of a data symbol part may be lowered if pilot boostingis performed. Accordingly, power boosting in which a reduction in theenergy of the data symbol part is taken into consideration may beperformed.

Two methods may be used as power boosting for a frame boundary symbol.

First, SP power may be maintained as in a normal data symbol, andinstead null carriers may be inserted. If null carriers are deployed,power of carriers other than the null carriers is increased becausepower is not distributed to the null carriers. Accordingly, there is anadvantage in that SP power is also increased. In this case, theaforementioned SP boosting power table has only to be used. That is, ifthis method is used, signaling overhead can be reduced because the SPboosting power table is used without a change, and the deterioration ofperformance can be minimized because proper energy is distributed to adata symbol.

Second, SP power boosting for a frame boundary symbol may be separatelyconfigured.

FIG. 38 shows the SP power boosting levels of a frame boundary symbol.

In the case of a frame boundary symbol, Dy=1 may be used, and thus apower boosting level may be determined depending on a Dx value.

A method of disposing null carriers and performing power boosting on aframe boundary symbol is described in detail below.

First, the elements/units of a system configuration for illustrating amethod of disposing null carriers in an SBS are described below.

Number of Carriers (NoC): the number of carriers including a pilot

Number of Active carriers (NoA): the number of active data carriers of anormal data symbol

N_SP: the number of Scattered Pilots (SPs)

N_SP-CP: the number of SP-bearing-CPs

N_NSP-CP: the number of non-SP-bearing-CPs

A_SP: the amplitude/size of an SP cell

A_CP: the amplitude/size of a CP cell

NoA_DATA,SBS: the number of data carriers of a Subframe Boundary Symbol(SBS)

NoA_SBS: the number of active data carriers of an SBS

N_SP,SBS: the number of SBS pilots

N_null: the number of null carriers

An SBS includes SBS pilots, that is, the Dx value and Dy=1 of an SPpattern which are used in the normal data symbol of a correspondingsubframe. Accordingly, if SP boosting power for a normal data symbol,such as that described above, is used, power of an SBS is greater thanpower of the normal data symbol except (L1_SP_boosting=‘000’) in whichboosting is not performed. Accordingly, in order to makeidentical/constant power of OFDM symbols that are transmitted andreceived, power of the OFDM symbol may be made identical with that of anormal data symbol by inserting a null carrier or a non-modulatedcarrier whose corresponding cell power is 0. A method of making power ofan SBS identical with power of a normal data symbol is described below.

NoA_SBS is the number of active data carriers of an SBS and may beobtained by subtracting the number of null carriers from the number ofdata cells of an SBS (i.e., NoA_SBS=N_DATA,SBS−N_null).

P _(NS)=NoA+(N _(SP) +N _(SP-CP))*A _(SP) ² +N _(NSP-CP) *A _(CP)²  [Equation 15]

In Equation 15, power of data carriers is assumed to be 1. Total powerof a normal data symbol may be obtained as in Equation 15. Power of anormal data symbol “P_NS” may be represented by the sum of power ofactive data carriers “NoA”, power of SPs “(N_SP+N_SP-CP)*(A_SP)̂2”, andpower of CPs “(N_NSP-CP)*(A_CP)̂2”.

P _(SBS)=NoA _(SBS) +N _(SP,SBS) *A _(SP) ² +N _(NSP-CP) *A _(CP)²  [Equation 16]

In Equation 16, power of data carriers is assumed to be 1. Furthermore,total power of an SBS may be obtained as in Equation 16. Total power ofan SBS “P SBS” may be represented by the sum of power of the active datacarriers of an SBS “NoA_SBS”, power of SBS pilots “(S_SP,SBS)*(A_SP)̂2”,and power of the CPs of the SBS “(N_NSP-CP)*(A_CP)̂2”.

Furthermore, as a result, the number of data carriers of the SBS inwhich total power of the normal data symbol of Equation 15 is equal tothe total power of the SBS of Equation 16 has only to be calculated.This is the same as Equation 17 below.

$\begin{matrix}{{NoA}_{SBS} = {{{NoA} - {\left( {N_{{SP},{SBS}} - N_{SP} - N_{{SP} - {CP}}} \right)*A_{SP}^{2}}} = {{NoA} - {\left( {N_{{SP},{SBS}} - {NoC} + {NoA} + N_{{NSP} - {CP}}} \right)*A_{SP}^{2}}}}} & \left\lbrack {{Equation}\mspace{14mu} 17} \right\rbrack\end{matrix}$

NoA_SBS indicates the number of active data carriers which may be usedto send the actual data of an SBS. Accordingly, NoA_SBS is the number ofactive data carriers of an SBS and thus may be obtained by subtractingthe number of null carriers from the number of data cells of an SBS(i.e., NoA_SBS=N_DATA,SBS−N_null). Inversely, the number of nullcarriers may be obtained by subtracting the number of active datacarriers of an SBS from the number of data carriers of the SBS.

An actual occupied bandwidth of a transmission signal frame may becontrolled depending on the NoC as in FIG. 33. That is, an actualoccupied bandwidth of a signal frame may be controlled by flexiblycontrolling the NoC, and a parameter regarding the NoC may be signaled.The NoC may be defined as in Equation 18.

NoC=NoC _(max) −C _(red) _(_) _(coeff) *C _(unit)  [Equation 18]

In Equation 18, NoC_max denotes a maximum number of carriers per symbol.C_red_coeff is a positive integer, and denotes a coefficient which ismultiplied by a control unit value “C_unit” and which determines thereduced number of carriers. C_red_coeff may also be designated as an NoCreduction coefficient. C_red_coeff has a value of 0˜4, which may besignaled as parameters. The parameters may be signaled as the NoCreduction coefficient of each preamble “L1B_preamble_reduced_carriers”,the NoC reduction coefficient of a first subcarrier“L1B_First_Sub_reduced_carriers”, and the NoC reduction coefficient ofsubcarriers subsequent to a second subcarrier “L1D_reduced_carriers.”The control unit value “C_unit” has a maximum Dx value. In other words,the control unit value is determined to be a maximum Dx valuecorresponding to the least common multiple of a Dx value having a basisof 3 and a Dx value having a basis of 4. The control unit value may bedetermined to be 96 with respect to 8K FFT, 192 with respect to 16K FFT,and 384 with respect to 32K FFT.

Table 34 below shows NoCs determined by Equation 18 with respect to FFTsizes and C_red_coeff.

TABLE 34 NoC C_red_coeff 8K FFT 16K FFT 32K FFT 0 6913 13825 27649 16817 13633 27265 2 6721 13441 26881 3 6625 13249 26497 4 6529 1305726113

In Table 34, the NoC if C_red_coeff=0 corresponds to the aforementionedNoC_max. 0˜4, that is, the values of C_red_coeff, may be signaled using3 bits. Hereinafter, the values of 0˜4 may be indicated by 000, 001,010, 011, and 100, respectively.

FIG. 39 shows the Number of Active carriers (NoA) for a normal datasymbol according to an embodiment of the present invention.

In FIG. 39, NoCs according to NoC reduction coefficients “C_red_coeff”have been shown in Table 34. As described above, in the case of a datasymbol, the number of active data carriers may be obtained bysubtracting the number of SPs and CPs from the NoC. Since CPs may beinserted into predetermined positions as predetermined numbers, the NoAmay be determined depending on the NoC reduction coefficient“C_red_coeff” and an SP pattern as in FIG. 39.

FIG. 40 shows the number of pilots of an SBS “N_SP,SBS” according to anembodiment of the present invention.

The NoC of a Subframe Boundary Symbol (SBS) may be determined asdescribed above. Subframe boundary pilots may be inserted into an SBS.The subframe boundary pilot may also be designated as an SBS pilot. Thesubframe boundary pilots may be inserted into positions which satisfy (kmod Dx=0) with respect to a carrier index k. In this case, a positionk=0 or k=NoC−1 is excluded from the position of the subframe boundarypilot because edge pilots are placed in the position. That is, an SBSpilot may use the Dx value of the SP pattern of the data symbol of acorresponding subframe, and may use a Dy value of 1.

In the embodiment of FIG. 40, the number of SBS pilots is indicative ofa number including edge pilots having pilot indices of k=0 and k=NoC−1.In some embodiments, the number of subframe boundary pilots may includethe number of edge pilots.

FIG. 41 shows the number of data carriers of an SBS according to anembodiment of the present invention.

The number of data carriers of an SBS may be obtained by subtracting thenumber of pilots from a total number of carriers of the SBS (i.e.,N_data,sbs=NoC−N_SP,SBS−N_NSP-CP).

FIG. 42 shows the number of CPs per symbol according to an embodiment ofthe present invention.

In FIG. 42, the number of CPs is also applied to an SBS because it isapplied to a frame in common. In an embodiment of the present invention,since SP-bearing-CPs are transmitted with SPs and power, the number ofCPs is indicative of the number of non-SP-bearing-CPs.

In Equation 17, the number of active data carriers of an SBS “NoA_SBS”may be obtained using the number of active data carriers per symbol“NoA”, the number of SPs of an SBS “N_SP,SBS”, the number of carriersper symbol “NoC”, the number of CPs per symbol “N_NSP-CP”, and amplitudeof SPs “A-SP”. The number of active data carriers per symbol “NoA”, thenumber of SPs of an SBS “N_SP,SBS”, the number of carriers per symbol“NoC”, the number of CPs per symbol “N_NSP-CP”, and amplitude of SPs“A-SP” denote the number of active data carriers per symbol “NoA” in thetable of FIG. 39, the number of SPs of an SBS “N_SP,SBS” in the table ofFIG. 40, the number of carriers per symbol “NoC” in Table 34 and FIGS.39-41, the number of CPs per symbol “N_NSP-CP” in FIG. 42, and amplitudeof SPs “A-SP” in the table of FIG. 35, respectively. Accordingly, thenumber of active data carriers of an SBS may be obtained based on theNoC reduction coefficient “C_red_coeff”.

FIGS. 43 to 47 show the number of active data carriers of an SBS“NoA_SBS” depending on the NoC reduction coefficient “C_red_coeff”according to an embodiment of the present invention.

FIG. 43 shows the number of active data carriers of an SBS if the NoCreduction coefficient is 0 (i.e., C_red_coeff=000).

FIG. 44 shows the number of active data carriers of an SBS if the NoCreduction coefficient is 1 (i.e., C_red_coeff=001).

FIG. 45 shows the number of active data carriers of an SBS if the NoCreduction coefficient is 2 (i.e., C_red_coeff=010).

FIG. 46 shows the number of active data carriers of an SBS if the NoCreduction coefficient is 3 (i.e., C_red_coeff=011).

FIG. 47 shows the number of active data carriers of an SBS if the NoCreduction coefficient is 4 (i.e., C_red_coeff=100).

The number of null carriers of an SBS may be obtained by subtracting thenumber of active data carriers of FIGS. 43 to 47 from the number of datacarriers of the SBS. An embodiment in which the number of null carriersis determined and a method of placing the number of null carriersdetermined as described above are described below. As described above,the broadcast signal transmitter configures a signal frame through theframe builder and frequency-interleaves the signal frame. Accordingly,in relation to frequency interleaving, a method of placing null carriersmay be different.

FIG. 48 shows a method of calculating the number of null carriers andpower normalization according to the method according to an embodimentof the present invention.

In FIG. 48, it is assumed that NoA=16, NoC=25, A_sp=2, A_CP=8/3,N_SP,SBS=9, N_DATA_SBS=13, and N_NSP-CP=3.

FIGS. 48(a) and 48(b) show subframe data symbols having SP patterns ofDx=6 and Dy=2. In FIGS. 48(a) and 48(b), total power of normal datasymbols in a frequency domain (FD) is 61.3 (FIG. 48(1)). The power ofthe normal data symbols may be calculated by Equation 15.

FIG. 48(c) shows an SBS before null carriers are inserted. Total powerof the SBS in the frequency domain (FD) before null carriers areinserted is 70.3. The power of the SBS may be calculated by Equation 16.

FIG. 48(d) shows an SBS after null carriers are inserted. Total power ofthe SBS after null carriers are inserted in the frequency domain (FD) is61.3.

The number of inserted null carriers is obtained by subtracting thenumber of active data carriers of the SBS from the number of datacarriers of the SBS (i.e., N_null=N_DATA,SBS−NoA_SBS=13−4=9). Power ofthe SBS is reduced from 70.3 to 61.3 by inserting the number of nullcarriers obtained as described above, thus being normalized identicallywith the power of normal data symbols (i.e., 61.3).

FIG. 49 shows a method of mapping the null carriers of an SBS accordingto an embodiment of the present invention.

FIG. 49 shows an embodiment in which frequency interleaving is performedafter frame mapping. In this specification, frequency interleaving maybe optionally performed. The reason for this is that if FrequencyDivision Multiplexing (FDM) is applied to a signal frame, when frequencyinterleaving is performed, the disposition of data according to FDM inthe frequency domain may be spread out due to the interleaving. Iffrequency interleaving is performed, data carriers and null carriers maybe sequentially mapped by taking the frequency interleaving intoconsideration. In this specification, carriers included in a symbol mayalso be designated as cells. A cell is indicative of a set of encodedI/Q components in a constellation.

As in FIG. 49, after data cells may be placed in carrier indices 1˜7,null cells may be placed. Furthermore, after interleaving, the datacells and the null cells are randomly spread out. Thereafter, pilots areinserted into predetermined positions in a pilot insertion block.

FIG. 50 shows a method of mapping the null carriers of an SBS accordingto another embodiment of the present invention.

FIG. 50 shows a method of mapping null carriers if frequencyinterleaving is not performed.

As in FIG. 50(a), data cells and null cells may be sequentially mapped.In this case, however, the data carriers are concentrated in one side ofa spectrum. In the edge area of a spectrum, an adjacent channel and atransmission/reception filter may deteriorate reception performance.Accordingly, data carriers may be placed at the center of a spectrum asmuch as possible in order to improve reception performance.

FIG. 50(b) shows a method of placing data cells at the center of afrequency spectrum and placing null cells in both edge areas. The methodof placing data cells at the center of a frequency spectrum may includea method of using the predetermined location of the center based on nullcell numbers and a method of signaling the start position of null cells.Such methods are additionally described later.

FIG. 51 shows a method of mapping the null carriers of an SBS accordingto another embodiment of the present invention.

FIG. 51 is a method of placing data cells at the center of a frequencyspectrum and shows a method of using the predetermined location of thecenter based on null cell numbers. The method of FIG. 51 may also becalled a simple direct mapping method.

In the embodiment of FIG. 51, it is assumed that the number of datacells of an SBS is 13 (N_DATA,SBS=13), the number of active data cellsof the SBS is 7 (NoA_SBS=7), and the number of null cells is 6(N_null=6).

The broadcast signal transmitter may place half of the null cells in thelowest frequency data carriers and may place the remaining half of thenull cells in the highest frequency data carriers. The number of nullcells placed in the lowest frequency may be obtained through a floorfunction “^(└)N_null/2^(┘)”, and the number of null cells placed in thehighest frequency may be obtained through a ceiling function“_(└)N_null/2_(┘).”

In FIG. 51(a), 3 of the 6 null cells are mapped to the lowest frequencydata carriers, and the remaining 3 null cells are mapped to the highestfrequency data carriers. Furthermore, pilots may be inserted as shown inFIG. 51(b).

FIG. 52 shows a method of mapping the null carriers of an SBS accordingto another embodiment of the present invention.

FIG. 52 is a method of placing data cells at the center of a frequencyspectrum and shows a method of signaling the start position of activedata cells. The method of FIG. 52 may also be called a boundary mappingmethod.

The broadcast signal transmitter may determine the start position ofdata cells depending on a frame configuration and may signal the startposition of determined active data cells. The null cells may be placedin the remaining indices other than the indices of the active datacells.

The broadcast signal transmitter may include information about the startof active data cells in an SBS “L1_SBS_NoA_Start” in the L1 signalingarea of a preamble and send the information. The broadcast signaltransmitter may select and dispose the positions of the data cells of anSBS according to circumstances. The broadcast signal receiver may beaware of the positions of active data carriers of the SBS by parsing theinformation “L1_SBS_NoA_Start” in the preamble. In an embodiment, theinformation “L1_SBS_NoA_Start” may use 15 bits because it has to support32K FFT. In an embodiment, in order to reduce signaling overhead, aposition may be controlled by four carriers and may be signaled in 13bits. Null carriers may be mapped before or after data carriers aremapped. The value of the information “L1_SBS_NoA_Start” may beindicative of the number of null cells inserted before active data cellsare inserted.

As in the embodiment of FIG. 52(a), since the value of the information“L1_SBS_NoA_Start” is 6, the active data cells are placed after 6 nullcells. FIG. 52(b) shows SBS carriers into which pilots have beeninserted.

The broadcast signal transmitter may optionally use the simple directmapping method of FIG. 51 and the boundary mapping method of FIG. 52. Inthis case, the broadcast signal transmitter may need to signal a methodof mapping null cells. In an embodiment, a method of mapping nullcarriers may be indicated using null carrier mapping information“L1_SBS_Null_Mapping.” The null carrier mapping information may beindicative of the simple direct mapping method or the boundary mappingmethod using 1 bit or 2 bits. The null carrier mapping information maybe included in the L1 signaling information of a preamble.

FIG. 53 shows a method of mapping null carriers according to anotherembodiment of the present invention.

FIG. 53 shows a method of evenly distributing null carriers in abandwidth. The method of FIG. 53 may also be called a distributedmapping method.

Null carriers may be distributed using a round function. Round operationmay be represented as follows.

round(k*(N_DATA,SBS−1)/(N_null−1)), k=0˜N_null−1

A floor function may be used instead of the round function. Furthermore,carrier indices not occupied by null cells may be placed in data cells.In the method of FIG. 53, a case where frequency interleaving is notperformed is assumed, and a data distribution effect in the frequencycan be improved although frequency interleaving is not performed.

All the methods of FIGS. 50 to 53 may be optionally used. The method ofFIG. 50 may also be called a general mapping method. That is, thegeneral mapping method of FIG. 50, the simple direct mapping method ofFIG. 51, the boundary mapping method of FIG. 52, and the distributedmapping method of FIG. 53 may be optionally used by the broadcast signaltransmitter, and a selected method may be signaled.

In the simple direct mapping method, data is placed at the corner of aband, and there is no signaling overhead. The simple direct mappingmethod may be implemented using a method that is the least complexityand simple.

In the boundary mapping method, data is placed at the center of a band,and there is no signaling overhead. Furthermore, data cells may be leastinfluenced by interference from an adjacent channel and channelestimation imperfection.

The general mapping method has signaling overhead, but can implementboth the simple direct mapping method and the boundary mapping methodthrough signaling information. Furthermore, a flexible systemconfiguration is possible.

In the distributed mapping method, data is distributed, and there is nosignaling overhead. A frequency diversity gain is increased, and nullcarriers may be used in interference sensing. However, system complexityis increased.

Since each of the four methods has the advantages and the disadvantages,all of the four methods or a subset of the four methods may be supportedby adding null mapping information to L1 signaling information asfollows.

SBS null carrier mapping information “L1_SBS_Null_Mapping” (2 bits): amethod of mapping null carriers of each SBS symbol.

“00”: Simple direct mapping (approach 1),

“01”: Boundary mapping (approach 2),

“10”: General mapping (approach 3),

“11”: Distributed mapping (approach 4)

If only some of the four methods are to be supported, the remainingcases may be designated as reserved fields. Alternatively, if the numberof signaling methods is 2 or less, it may be reduced to 1 bit. Inaddition to the four methods, in preparation for null carrier mappingmode, L1_SBS_Null_Mapping may be extended to 3 bits and used as areserved field.

If a Frequency Interleaver (FI) is used, the simplest method of selectedmethods may be used if the FI is off because the output of the FI is notgreatly influenced by a distribution of the null cells of input. In thiscase, in a method of mapping null carrier when the FI is on, a methodautomatically designated when the FI is on may be designated to be usedwith reference to information that belongs to L1 signaling informationand that is indicative of FI on/off.

For example, if L1_frequency_interleaver=“1” (FI enable), the simpledirect mapping or boundary mapping method may be automaticallydesignated to be used. In this case, the broadcast signal receiver maydetermine a method of mapping the null carriers of an SBS with referenceto L1_frequency_interleaver, may check the positions of correspondingdata cells, and may perform decoding.

Dummy cells may be included in a data cell of an SBS. In this case, thenumber of active data cells of the SBS may be the sum of the number ofactual data cells and the number of dummy cells. In this case, theaforementioned method of mapping null cells may be identically appliedexcept that the aforementioned data cells include dummy cells.

FIG. 54 shows a method of transmitting a broadcast signal according toan embodiment of the present invention.

As described above in relation to the broadcast signal transmitter andthe operation thereof, the broadcast signal transmitter may inputprocess the input data using the input formatting module and output atleast one Data Pipe (DP), that is, Physical Layer Pipe (PLP) data(S54010). Furthermore, the broadcast signal transmitter mayerror-correction process or FEC-encode data included in at least one PLPusing the BICM module (S54020). The broadcast signal transmitter maygenerate a signal frame, including the data of the at least one PLP,using the framing module (S54030). The broadcast signal transmitter mayinsert pilots into the signal frame using the pilot insertion module(S54040) and OFDM-modulate the signal frame using the IFFT module(S54050).

The signal frame includes a preamble and at least one subframe.Furthermore, the inserted pilots include Continual Pilots (CPs) andScattered Pilots (SPs). In an embodiment, preamble pilots may beinserted into the preamble, and a subframe boundary preamble may also beinserted into an SBS.

Amplitude of SPs is determined based on an SP boosting parameter and theSP pattern of the SPs. The SP boosting parameter includes the fivelevels of each SP pattern. The five levels include a particular levelindicating 0 dB at which power boosting is not performed. The broadcastsignal transmitter may select one of the five levels, may boost the SPsbased on amplitude of a corresponding level, and may send the boostedSPs.

The preamble includes SP boosting information. The SP boostinginformation indicates amplitude or a boosting level of the SPs. The SPboosting information may signal the SP boosting parameter in 3 bits.That is, the SP boosting information is signaled as the value of one of“000”˜“100”, and thus the broadcast signal receiver may check theamplitude of the SPs by combining the SP pattern information, the SPboosting tables according to SP patterns, such as those of FIGS. 34 and35, and the reception SP parameter. The SP pattern information isincluded in the preamble and signaled.

Amplitude of subframe boundary pilots is determined based on theaforementioned SP boosting information or SP boosting parameter. Thebroadcast signal receiver may be aware of the positions of subframeboundary pilots based on the SP pilot pattern of a subframe and may beaware of amplitude of subframe boundary pilots based on received SPboosting information.

Subframe boundary pilots are placed at a pilot interval in the frequencydirection of the SP pattern of a subframe, that is, at the Dx intervalof a subframe. Furthermore, for power normalization, the data carriersof an SBS may include a specific number of active data carriers and aspecific number of null carriers.

The number of active data carriers of an SBS is determined based on anSP boosting parameter. For example, if amplitude of a subframe boundarypilot is greatly boosted, the number of active data carriers may bereduced and the number of null carriers may be increased in order tomeet power with a data symbol. Alternatively, If amplitude of a subframeboundary pilot is small boosted, the number of active data carriers maybe increased, and the number of null carriers may be reduced or omitted.For example, if power boosting is not performed because the value of anSP boosting parameter is 0, a null carrier may not be required.

The number of null carriers is also determined based on amplitude ofSPs. Amplitude of SPs is determined based on an SP boosting parameter,and the determined amplitude is also applied to a subframe boundarypilot. Accordingly, as described above, if amplitude of SPs isincreased, the number of null carriers may be increased becauseamplitude of subframe boundary pilots is also increased. Furthermore, ifamplitude of SPs is reduced, the number of null carriers may also bereduced because amplitude of subframe boundary pilots is also reduced.

As described above, the number of null carriers may be obtained bysubtracting the number of active data carriers from the number of datacarriers of a subframe boundary symbol. A method of obtaining the numberof data carriers of an SBS, the number of active data carriers of anSBS, and the number of null carriers of an SBS is the same as thatdescribed above.

The number and positions of inserted null carriers may be determined asdescribed with reference to FIGS. 48 to 53. In an embodiment, activedata carriers may be placed in the center of all data cells, and half ofnull carriers may be placed in each band edges. ½ of null cells mayoccupy the lowest-frequency data carriers, and the remaining ½ of thenull cells may occupy the highest-frequency data carriers. Furthermore,data carriers between two sets of null carriers may become active datacarriers.

FIG. 55 shows the synchronization and demodulation module of thebroadcast signal receiver according to an embodiment of the presentinvention.

The synchronization and demodulation module includes a tuner 55010 fortuning a broadcast signal, an ADC module 55020 for converting a receivedanalog signal into a digital signal, a preamble detector 55030 fordetecting a preamble included in the received signal, a guard sequencedetector 55040 for detecting a guard sequence included in the receivedsignal, a waveform transform module 55050 for performing OFDMdemodulation, that is, FFT, on the received signal, a reference signaldetector 55060 for detecting a pilot signal included in the receivedsignal, a channel equalizer 55070 for performing channel equalizationusing the extracted guard sequence, an inverse waveform transform module55080, a time domain reference signal detector 55090 for detecting thepilot signal in a time domain, and a time/frequency sync module 55100for performing time/frequency synchronization on the received signalusing the preamble and the pilot signal.

The waveform transform module 55050 may also be designated as an FFTmodule for performing OFDM demodulation. The inverse waveform transformmodule 55080 is a module for performing transform opposite FFT and maybe omitted according to embodiments or may be replaced with anothermodule for performing the same or similar function.

FIG. 55 corresponds to a case where the broadcast signal receiverprocesses a signal, received by a plurality of antennas, through aplurality of paths. In FIG. 55, the same modules are illustrated inparallel, and a redundant description of the same module is omitted.

In an embodiment of the present invention, the broadcast signal receivermay detect and use a pilot signal using the reference signal detector55060 and the time domain reference signal detector 55090. The referencesignal detector 55060 may detect the pilot signal in a frequency domain.The broadcast signal receiver may perform synchronization and channelestimation using the characteristics of the detected pilot signal. Thetime domain reference signal detector 55090 may detect the pilot signalin the time domain of a received signal. The broadcast signal receivermay perform synchronization and channel estimation the characteristicsof the detected pilot signal. In this specification, at least one of thereference signal detector 55060 for detecting the pilot signal in thefrequency domain and the time domain reference signal detector 55090 fordetecting the pilot signal in the time domain may be called a pilotsignal detector or a pilot detector. Furthermore, in this specification,a reference signal means a pilot signal.

FIG. 56 shows a method of receiving a broadcast signal according to anembodiment of the present invention.

As described above in relation to the broadcast signal receiver and theoperation thereof, the broadcast signal receiver may OFDM-demodulate areceived broadcast signal using the Fast Fourier Transform (FFT) module(S56010). The broadcast signal receiver may detect pilots, included inthe broadcast signal, using the pilot detector (S56020). The broadcastsignal receiver may perform synchronization, channel estimation, andcompensation on the broadcast signal using the detected pilots. Thebroadcast signal receiver may parse the signal frame of the broadcastsignal using the frame parsing module (S56030). The broadcast signalreceiver may extract and decode preamble data included in the signalframe and may extract a required subframe or PLP data using L1 signalinginformation obtained from the preamble data. The broadcast signalreceiver may convert the PLP data extracted from the broadcast signalinto a bit domain using the demapping and decoding module and mayFEC-decode the PLP data (S56040). Furthermore, the broadcast signalreceiver may output the PLP data in the form of a data stream using theoutput processing module (S56050).

The signal frame includes a preamble and at least one subframe.Furthermore, the inserted pilots include Continual Pilots (CPs) andScattered Pilots (SPs). In an embodiment, preamble pilots may beinserted into the preamble, and a subframe boundary preamble may also beinserted into an SBS.

Amplitude of SPs is determined based on an SP boosting parameter and theSP pattern of the SPs. The SP boosting parameter includes the fivelevels of each SP pattern. The five levels include a particular levelindicating 0 dB at which power boosting is not performed. The broadcastsignal transmitter may select one of the five levels, may boost the SPsbased on amplitude of a corresponding level, and may send the boostedSPs.

The preamble includes SP boosting information. The SP boostinginformation indicates the amplitude or boosting level of the SPs. The SPboosting information may signal the SP boosting parameter in 3 bits.That is, the SP boosting information is signaled as the value of one of“000”˜“100”, and thus the broadcast signal receiver may check theamplitude of the SPs by combining the SP pattern information, the SPboosting tables according to SP patterns, such as those of FIGS. 34 and35, and the reception SP parameter. The SP pattern information isincluded in the preamble and signaled.

Amplitude of subframe boundary pilots is determined based on theaforementioned SP boosting information or SP boosting parameter. Thebroadcast signal receiver may be aware of the positions of subframeboundary pilots based on the SP pilot pattern of a subframe and may beaware of amplitude of subframe boundary pilots based on received SPboosting information.

Subframe boundary pilots are placed at a pilot interval in the frequencydirection of the SP pattern of a subframe, that is, at the Dx intervalof a subframe. Furthermore, for power normalization, the data carriersof an SBS may include a specific number of active data carriers and aspecific number of null carriers.

The number of active data carriers of an SBS is determined based on anSP boosting parameter. For example, if amplitude of a subframe boundarypilot is greatly boosted, the number of active data carriers may bereduced and the number of null carriers may be increased in order tomeet power with a data symbol. Alternatively, If amplitude of a subframeboundary pilot is small boosted, the number of active data carriers maybe increased, and the number of null carriers may be reduced or omitted.For example, if power boosting is not performed because the value of anSP boosting parameter is 0, a null carrier may not be required.

The number of null carriers is also determined based on amplitude ofSPs. Amplitude of SPs is determined based on an SP boosting parameter,and the determined amplitude is also applied to a subframe boundarypilot. Accordingly, as described above, if amplitude of SPs isincreased, the number of null carriers may be increased becauseamplitude of subframe boundary pilots is also increased. Furthermore, ifamplitude of SPs is reduced, the number of null carriers may also bereduced because amplitude of subframe boundary pilots is also reduced.

As described above, the number of null carriers may be obtained bysubtracting the number of active data carriers from the number of datacarriers of a subframe boundary symbol. A method of obtaining the numberof data carriers of an SBS, the number of active data carriers of anSBS, and the number of null carriers of an SBS has been described above.All of or some of the tables of FIGS. 38 to 47 may be stored in thebroadcast signal transmitter and the broadcast signal receiver and used.

The number and positions of inserted null carriers may be determined asdescribed with reference to FIGS. 48 to 53. In an embodiment, activedata carriers may be placed in the center of all data cells, and half ofnull carriers may be placed in each band edges. ½ of null cells mayoccupy the lowest-frequency data carriers, and the remaining ½ of thenull cells may occupy the highest-frequency data carriers. Furthermore,data carriers between two sets of null carriers may become active datacarriers.

In accordance with an embodiment of the present invention, sync trackingon the reception side and signal processing performance, such as channelestimation, can be improved by boosting power of an SP. Furthermore,system flexibility can be improved because one of the five levels isused as a level for boosting power of an SP without fixing the level.The broadcast system allows an efficient power distribution because aboosting level is determined by taking into consideration the channelenvironment, service importance, the amount of data, and available powerof a corresponding system. Furthermore, flexible and efficient signalprocessing is made possible because a boosting level is checked based onSP boosting information and an SP is processed based on the boostinglevel on the reception side. Only when such a boosting level issignaled, the broadcast signal receiver can process a signal accordingto a boosting level of the broadcast signal transmitter.

Furthermore, the broadcast signal transmitter can minimize the energyshortage of data carriers by performing boosting on a subframe boundarypilot like the SP of a subframe and additionally disposing nullcarriers. The broadcast signal transmitter/broadcast signal receiver mayreduce signaling overhead because SP boosting table/information can beused.

In the case of an SBS, if the SP boosting tables and SP boostinginformation for a subframe are used, signaling overhead is reducedbecause pilot density is increased, but power of a signal frame persymbol may vary. If power of each symbol is different, the filter andamplifier complexity of a system may be increased and/or channelestimation/sync tracking performance may be deteriorated. Accordingly,in an embodiment of the present invention, power of each symbol within asubframe can be regularly maintained by inserting null carriers into anSBS. Accordingly, system complexity can be reduced and signal processingperformance can be improved because evenly distributed power is used ineach symbol and pilots having the same amplitude are used on thereception side.

In particular, inter-symbol/inter-frequency interference can beminimized and signal decoding performance can be further improved byplacing null carriers in both edge areas of a band and placing activedata carriers in the center of the bandwidth. Furthermore, signalingoverhead can be reduced because the positions of null carriers andactive data carriers do not need to be additionally signaled. Inparticular, channel estimation/sync tracking speed using a subframeboundary pilot can be improved, and system latency can be reduced.

Those skilled in the art will understand that the present invention maybe changed and modified in various ways without departing from thespirit or range of the present invention. Accordingly, the presentinvention is intended to include all the changes and modificationsprovided by the appended claims and equivalents thereof.

In this specification, both the apparatus and the method have beendescribed, and the descriptions of both the apparatus and method may bemutually supplemented and applied.

The present invention is used in a series of broadcast signal providingfields.

It is evident to those skilled in the art will understand that thepresent invention may be changed and modified in various ways withoutdeparting from the spirit or range of the present invention.Accordingly, the present invention is intended to include all thechanges and modifications provided by the appended claims andequivalents thereof.

What is claimed is:
 1. A broadcast signal transmitter, comprising: aninput formatting module configured to input process input data and tooutput at least one Physical Layer Pipe (PLP) data; a Bit Interleavedand Coded Modulation (BICM) module configured to perform errorcorrection processing on the PLP data; a framing module configured togenerate a signal frame comprising the PLP data, the signal framecomprising a preamble and at least one subframe; a pilot insertionmodule configured to insert pilots into the signal frame; and an InverseFast Fourier Transform (IFFT) module configured to OFDM-modulate thesignal frame, wherein the subframe comprises data symbols and at leastone Subframe Boundary Symbol (SBS), and the SBS comprises data carriersand subframe boundary pilots.
 2. The broadcast signal transmitter ofclaim 1, wherein: the data symbols of the subframe comprises ScatteredPilots (SPs), amplitude of the SPs is determined based on an SP boostingparameter indicating a power boosting level of the SPs, and amplitude ofthe subframe boundary pilots is determined based on the SP boostingparameter.
 3. The broadcast signal transmitter of claim 2, wherein: thesubframe boundary pilots are placed based on a pilot separation in afrequency direction of an SP pattern for the subframe, and the datacarriers of the SBS comprise a specific number of active data carriersand a specific number of null carriers.
 4. The broadcast signaltransmitter of claim 3, wherein the number of active data carriers isdetermined based on the SP boosting parameter.
 5. The broadcast signaltransmitter of claim 3, wherein the number of null carriers isdetermined based on the amplitude of the SPs.
 6. The broadcast signaltransmitter of claim 3, wherein the number of null carriers is obtainedby subtracting the number of active data carriers from the number ofdata carriers.
 7. The broadcast signal transmitter of claim 3, wherein:the active data carriers are placed at a center of the data carriers,and half of the null cells are placed at each band edges of the datacarriers.
 8. A method of transmitting a broadcast signal, comprising:input processing input data and outputting at least one Physical LayerPipe (PLP) data; performing error correction processing on the PLP data;generating a signal frame comprising the PLP data, the signal framecomprising a preamble and at least one subframe; inserting pilots intothe signal frame; and OFDM-modulating the signal frame, wherein thesubframe comprises data symbols and at least one Subframe BoundarySymbol (SBS), and the SBS comprises data carriers and subframe boundarypilots.
 9. The method of claim 8, wherein: the data symbols of thesubframe comprises Scattered Pilots (SPs), amplitude of the SPs isdetermined based on an SP boosting parameter indicating a power boostinglevel of the SPs, and amplitude of the subframe boundary pilots isdetermined based on the SP boosting parameter.
 10. The method of claim9, wherein: the subframe boundary pilots are placed based on a pilotseparation in a frequency direction of an SP pattern for the subframe,and the data carriers of the SBS comprise a specific number of activedata carriers and a specific number of null carriers.
 11. The method ofclaim 10, wherein the number of active data carriers is determined basedon the SP boosting parameter.
 12. The method of claim 10, wherein thenumber of null carriers is determined based on the amplitude of the SPs.13. The method of claim 10, wherein the number of null carriers isobtained by subtracting the number of active data carriers from thenumber of data carriers.
 14. The method of claim 10, wherein: the activedata carriers are placed at a center of the data carriers, and half ofthe null cells are placed at each band edges of the data carriers.